FAUNA OF THE ST. JOHN GROUP. 270 
shale in which P. pontificalis occurs, with this species the pygidia of this group seems to 
have an affinity in the fineness of the raised lines of the upper surface. 
The third group of pygidia is about as plentifully represented in the Saint John slates 
as the preceding, and is most abundant at the same horizon. Fragments of the cephalic 
shield of a large undescribed trilobite occur with these pygidia. 
Type C a (Fig. 20). 
Pygidium obovate-lanceolate, and about two-sevenths longer than wide. 
Axial lobe ovate-lanceolate, about half the length of the pygidium. There are three 
rings at the anterior end, of which the first is much more distinct than the others; from 
the back of the first ring a lunate segment of about half the length of the ring is marked 
off by a faint furrow. The third ring is scarcely distinguishable. 
Marginal third—The inner zone is strongly elevated at the back of the axial lobe 
whence a ridge runs forward obliquely on each side, toward the anterior end of the pygi- 
dium. The outer zone is convex near the posterior margin, but the convexity is greater in 
the anterior half. There is amarkedsinusat the posterior end of the pygidium about two- 
thirds as wide as the front of the axial lobe. 
Sculpture —The test has a smooth and rather dull surface. 
Type C b (Fig. 21.) 
Pygidium oblanceolate, longer than wide, by about three-quarters of it traverse 
diameter. 
Axial lobe broadly ovate, about as long as wide, and more than a third of the whole 
length of the pygidium, moderately convex. One ring distinctly marked off, and another 
faintly indicated on the axial lobe. A faint furrow sets off a lunate area from the first 
ring, which area extends along the back of the ring for more than a third of its length. 
Two short furrows or depression are found near the edge of the axial lobe in its posterior 
half, where there is also a longitudinal furrow or groove on the line of the axis (perhaps 
accidental.) 
Marginal third—The inner part is strongly elevated behind the axil lobe, the eleva- 
tion descending to a point towards the extremity of the pygidium. The outer zone is con- 
vex in front, but flattens out toward the extremity of the pygidium, where it seems to be 
emarginate. 
Sculpture.—The surface is smooth and shining, but very finely granulate under the 
lens. Near the outer margin on each side of the pygidium are about six anastomosing 
raised lines, nearly parallel to its edge. The under surface of the pygidium is traversed by 
numerous raised lines which arch around the axial lobe; on the elevated part of the mar- 
ginal area there are about eighteen (18) such lines, of which those next the lobe are closely 
crowded together; on the posterior flat part there are about eight (8) lines separated by 
about the space of two millimetres. 
Length—All the pygidia of this type were nearly or quite one inch in length. 
From Portland, N. B., in Div. te. 
