Illustrations of the Fauna of the St. John Group.

By G. F. MATTHEW, M.A.

(Presented May 26, 1883).

No. I.-THE PARADOXIDES.

(Supplementary Section describing the Parts).

MOVEABLE CHEEKS.

No. 1. (Figs. 5, 6 (& 11 ?).

Distinguished by the width of the inner end of the cheek, which is about one-third as long as the posterior margin, from the base of the genal spine.

At and near the front end of the cheek the flat area and the fold are of about equal width. The eyelobe suture is strongly arched. The genal spine is nearly twice as long as the posterior margin. The posterior marginal fold is narrow throughout, and at the inner end scarcely half as wide as the flat area.

Sculpture. The anterior marginal fold is traversed on the upper side by about eight (8) parallel, anastomosing, raised lines, and on the under side by about eight (8) or ten (10). Half way down the spine there are about nine (9) raised lines, most distinct on the outer half. The posterior marginal fold has on the upper surface four (4) or five (5) fine, raised lines, crowded along its outer margin. The flat area is smooth and somewhat lustrous. Length, two (to two and a half) inches.

Found at Portland and Radcliff Stream in Division 1c.

This cheek may belong to P. suricoides.

No. 2. Figs. (1 & 3).

Distinguished by its large and massive genal spine.

The flat area is more triangular than that of No. 1. The inner end of the cheek in the adult is only about one quarter of the length of the posterior margin. The genal spine stands out at an angle of 20 or 30 degrees from the posterior margin, and is more than twice as long as that part: it is nearly straight for three-quarters of its length, but strongly incurved at the tip.

Sculpture. The anterior marginal fold is traversed on the upper surface at the genal angle by about eleven (11) raised lines (those on the outer third crowded together)*: half-way down the spine are about twelve (12) lines equally distributed. On the under surface of

*This crowding of the lines is common to the cheeks of several species.

the anterior marginal fold are about thirteen (13) lines (those toward the inner side more closely set), and of these about six (6) go around the genal angle outside of the flat area: half-way down the spine are about fifteen (15) lines evenly distributed. No raised lines were observed on the posterior marginal fold.

Length, about two inches.

Found at Portland in Division 1c.

No. 3. (Fig. 2).

Distinguished from the two preceding and from No. 5 by its small genal spine.

The flat area is more triangular than No. 1, but less so than No. 2; as in the former, the inner end of the cheek is wide, being nearly half of the length of the posterior margin. The anterior marginal fold and spine are strongly arched. The spine is about one quarter longer than the posterior margin, and much narrower than the anterior marginal fold.

Sculpture. The anterior marginal fold has on the upper side, at the genal angle, about eighteen or twenty (18-20) fine raised lines more evenly distributed than those of the preceding forms. The flat area appears smooth and shining, but under the lens is seen to be minutely granulated.

Length, about one and a half inches.

Found at Radcliff's Mill-stream, Simonds: from Division 1d, and therefore higher in geological position than any of the others. It may be the young of a variety of No. 5. In the wide posterior end of the flat area, and in the numerous fine raised lines of the anterior marginal fold, it exhibits analogies to P. quacoensis.

No. 4. (Figs. 7 & 12. (9 & 10?)

Distinguished by the long eyelobe, and the narrow, anterior end of the flat area. The inner end of the cheek is about one-third of the length of the posterior margin (longer in adults). The spine is not quite as long as the anterior marginal fold, and the two parts are regularly curved. The anterior third of the flat area is about half as wide as the corresponding part of the marginal fold.

Sculpture. On the upper side of the anterior marginal fold are about eight (8) lines, and about ten are found half-way down the spine. The surface of the flat area is minutely but distinctly granulated, but these granulations are usually not distinguishable without a lens: in adults this part of the cheek is somewhat undulated. There are large specimens apparently belonging to this species in which the raised lines of the anterior marginal fold are reduced to five (5), and the surface of the flat area is smoother than in medium and smaller sized cheeks.

Length, about two inches.

Found at Portland and Radcliff's Stream in Division 1c.

This cheek may belong to P. eteminicus.

No. 5. (Fig. 8).

Distinguished from all the others by the numerous raised lines on the anterior marginal fold and genal spine, and by the breadth and flatness of these parts.

The posterior part of the flat area is very wide, and the spine long and regularly curved. The margin of the flat area is not well defined.

Sculpture. The upper side of the anterior marginal fold is marked at the genal angle by from twenty-five to thirty-five (25-35) fine, raised lines (most numerous in the adult): these lines are more irregular and anastomose more frequently than in the other species. Half-way down the genal spine these lines are reduced in number to about twenty (20). The posterior marginal fold has two or three (2-3) fine lines crowded along the outer margin, and at the genal angle about eight (8) broken lines running around outside the outer corner of the flat area. The flat area is smooth with an undulated surface, and has about three stria (not raised lines) crowded along the edge of the ocular suture. Length, from three to three and a half inches.

Found at Portland in Division 1c.

This species in the numerous lines on the anterior margin is allied to P. quacoensis and P. pontificalis, in size it is nearer the latter, but in the great width of the posterior part of the flat area, it resembles the former.

No. 6. (Fig. 4).

Distinguished from the others by its small size and granulated flat area.

The genal spine is nearly one and a half (13) times as long as the posterior margin, and is strengthened by a keel which runs lengthwise along its surface about one-third from the outer margin: the spine is not much arched and is much narrower than the anterior marginal fold. The narrow anterior part of the flat area is about two-thirds (3) of the width of the anterior marginal fold.

Sculpture. The anterior marginal fold has about nine (9) strong, raised lines on the under surface (but the upper surface is nearly smooth). The genal spine has on the upper side about four raised lines visible only with a lens; these lines are between the keel and the inner margin of the spine. No raised lines were detected on the posterior marginal fold, but its surface appears minutely granular under the lens. The surface of the flat area is granulated, the markings being just visible to the naked eye, and largest at the outer angle. Length, nearly three-quarters of an inch.

Found at Portland, N.B., in Division 1c.

This cheek, in its markings and its small size, appears to come nearer to P. acadica than to any other species known in the St. John Group.

THORACIC SEGMENTS.

The material in my possession representing this part of the body of the Saint John Paradoxides (the thorax) are too fragmentary to enable me to obtain any satisfactory results from their study. There were however one or more species in which some of the lateral appendages of the thorax were extravagantly prolonged.

PYGIDIA.

There are three distinct types of pygidia found with the Paradoxides that occur at Saint John. One of these groups of forms may be described, as orbicular-ovate (A), another as orbicular-obcordate (B), and the third as obcordate-lanceolate (C).

Sec. IV., 1883. 35.

The first type (A), which is also the smallest, is, frequently met with, and exhibits a considerable variety of forms. From their abundance it is supposed that these pygidia pertain to P. eteminicus and its allies. They have a marked sinus at the extremity. I figure and describe the principal varieties observed.

All the pygidia of this type were found at Portland in Div. 1c.

Type A a (Fig. 16.)

Nearly orbicular and about as wide as long.

Axial lobe about one third of the whole length and but slightly raised above the general level of the pygidium; a narrow ring in front is divided by a distinct furrow from the semi-circular posterior segment.

Marginal third.-There is a raised crescent-shaped tract behind and higher than the axial lobe, and a depressed zone of the pygidium encloses this tract and the axial lobe. The marginal zone is slightly convex in the anterior half, but flat behind, where there is a marked sinus two thirds as wide as the front of the axial lobe.

Sculpture. The surface is shining and minutely granular; the granulations are most distinct on the front of the elevated tract behind the axial lobe,

This is the only pygidium found at Saint John (Portland) which has a semi-circular axial lobe, and it perhaps belongs to some other species than P. eteminicus.

Type Ab (Fig. 17.)

Broadly ovate and about one sixth wider than long.

Axial lobe more than half of the whole length of the pygidium; ovate-conical, moderately convex: first ring sharply divided off from the rest of the lobe, and having a narrow lunate segment, of about half its length, marked off from the posterior side: a second ring is indicated by faint depressions on the axis: the remainder of the lobe has two points or faint ridges which are directed forward toward the axial line.

Marginal third.-The inner zone of the marginal area is raised into a strong elevation just behind the end of the axial lobe, which elevation in young individuals has the appearance of a tubercule. The outer zone is moderately convex in the anterior half and flattened at the posterior part, where it is also truncated, or slightly arched inward at the margin.

Sculpture. The whole surface is shining and minutely granulate or pitted, the most distinct pits being on the axial lobe; The posteror quarter of the marginal area is wrinkled, and along the sinus at the end are two or three faint, raised lines.

Type A c (Fig. 18.)

Pygidium ovate, and as long as wide.

Axial lobe half of the whole length of the pygidium; broad-ovate, moderately convex; bounding furrow rather faintly marked. One ring faintly indicated.

Marginal third. The inner zone is but slightly marked off from the outer, and bears a sharp elevated ridge (perhaps due to an accident of preservation) which arches across from side to side, around the extremity of the axial lobe. Outer zone as in b, but the sinus deeper and about three quarters of the width of the axial lobe.

Sculpture.-Appears dull and velvety to the naked eye, but under the lens is seen to be minutely granulate: the under side of the pygidium is marked by concentric raised lines, which on the posterior part are separated by about the space of half a millimetre, and are rudely parallel to the crescent-like ridge on the middle of the pygidium.

Type A d (Fig. 19.)

Pygidium rhombic-ovate and about as wide as long.

Axial lobe lance-ovate in form and three-fifths of the length of the whole pygidium: moderately convex in the anterior two thirds, but flattened and scarcely distinguishable from the marginal area in the posterior third. Only one ring at the anterior end of the axial lobe; from the back of this ring a narrow, lunate segment is marked off by a light furrow extending across the lobe.

Marginal third is impressed in its anterior part by grooves originating from the ends of the furrows bounding the axial ring; the points of these impressions are bent toward the axial lobe, but do not reach it extremity: two faint depressions parallel to the outer margin, traverse the rest of the marginal area. On the axial line there is a small ovateacuminate plate, which occupies more than half of the space from the point of the axial lobe to the posterior extremity of the pygidium. This part of the pygidium is sinuate, having a shallow indentation about two thirds as wide as the front of the axial lobe. Sculpture. The whole surface is shining and under the lens is minutely tuberculose. No raised lines are visible except a few near the posterior margin; these are transverse to the length of the pygidium and rudely parallel to each other.

Length of the forms of this type vary from half an inch to seven-eighth's of an inch.

The pygidia of the second group (B), are considerably larger than those above described and were all found in the soft dark grey shale in the upper part of Division 1c. They are characterized by a shallow sinus with rounded corners, which is sometimes only a slight waving inflection of the posterior margin. The following are the principal varieties.

Type B a (Fig. 13.)

Obcordate and about one-eighth wider than long.

Axial lobe about two thirds of the length of the whole pygidium; ovate and somewhat longer than wide; moderately convex and distinctly bounded. There is a broad ring in front, which with the anterior furrow and articulating front of the pygidium form about one third of the whole lobe. There are indications of a second ring of about the same width as the first.

Marginal third.-The inner zone is flat and without special features, the outer zone is moderately convex in the anterior two thirds, flat elsewhere and sinuate at the base; the sinus is shallow and about one quarter wider than the front of the axial lobe.

Sculpture. The axial lobe is smooth and velvety; the marginal area is also smooth, but more glossy than the axial lobe. A few faint lines were observed close along the pos