BULLETIN OF THE LABORATORIES 
70 
length and the margin is greatly rounded and exhibits (sub-epidermal?) 
striations. The eyes are unfortunately destroyed in all specimens seen, 
but evidently were large. The suture separating the fixed cheeks is 
also obliterated, but its position is approximately indicated in our 
figure. 
The thorax consists of ten distinctly separated segments. The 
axial portion is high and evenly convex and the lateral portions are 
rather abruptly flexed near the middle of their width and the plurae 
are high and convex, not sulcate. The pigidium is one third wider 
than long (Shumard’s specimen was a fragment).and the postero-lateral 
outline is a perfect arc of a circle, whose centre lies axially about four- 
fifths its length from the posterior extremity of the pigidium. The 
axial portion is high and tumidly conical and rather obtuse, the mar- 
ginal sulci being rather deep. The pleural portions are convex and 
descend rapidly peripherally to the plane of the wide, convex, smooth 
border which is unmarked or ornamented with concentric striations. 
The axial segments are ten or eleven and are not sulcate, while the 
eight or nine pleural ribs are distant and prominent and bifurcate to- 
ward the outer end. Entire length, 1,80; width, i.oo; axial length 
of head, .50; entire length, .85; length of pigidium, .70; width 
of pigidium, i.oo; width of axial lobe of pigidium, .35; width of 
axial lobe of thorax anteriorly, .40. 
Shumard’s statement that the margin of the pigidium is concave, 
was due to the exfoliation of that portion of the specimen. Several 
of our specimens are in the same state of preservation. 
Note. — Phillipsia elliptica^ M. and W. which, by a curious over- 
sight, was omitted from our list, is much more like P. swallovi than 
the present species. Refer to Pal. 111 ., vol. Ill, p. 460; Plate 14, 
Eig. 8. 
