238 Systematic Paleontology 



outer one made up of 4 or 5 right posterior plates, 3 minute pieces on the 

 left, and plate 13. The inner pyramid is not preserved in the specimen at 

 hand. 



This species is most closely related to P. elongalus, but the greater size 

 and elongated theca of the latter will readily distinguish it. P. clarki is 

 similar, but the greater size, oval outline, and the differently sculptured 

 plates will serve to identify it. 



Length of the only known specimen 16 mm.; width 12 mm.; depth 9 

 mm. The base of the theca is comparatively large, indicating a stout 

 column ; the oral end is flattened. Between the two flattened ends the 

 theca is slightly convex, giving it the subquadrate outline indicated by 

 the specific name. The sculpturing of the thecal plates is decidedly 

 vermiculate, and not radiate as in most other species. 



Occurrence. — Helderberg Formation, Keyser Member. Devil's 

 Backbone. 



Collection. — U. S. National Museum. 



PSEUDOCRINITES ABNORMALIS Schuchert 



Plate XXXIII, Figs. 10-12 



Pseudocrinites abnormalis Schuchert, 1904, Smith. Misc. Col., vol. xlvii, pt. ii, 

 No. 1482, pp. 231, 232, pi. xxxv, figs. 10-12; text fig. 30. 



Description. — Pectinirhombs about equally large and each has from 65 

 to 70 folds. Basal pectinirhomb on plates 5 and 6 and not, as usual in this 

 genus, on plates 1 and 5. In other words, this pectinirhomb is confined to 

 the second circle of plates and is not divided, one-half of the rhomb being 

 in the basal and the other half in the second row. Ambulacra as in P. 

 gordond, with about 34 brachioles on one side of each ambulacrum. 



This species has the general expression of P. gordoni, except that the 

 outline of the theca is regularly oval instead of nearly circular. It differs, 

 also, in having the basal pectinirhomb on plates 5 and 6 instead of on plates 

 1 and 5. That the two forms are really closely related is shown by the ar- 

 rangement of the anal plates. In P. abnormalis, as in P. gordoni, these 

 are composed of 2 complete circles of plates, while in the group typified 

 by P. clarki the outer circle consists of plate 13 and several small pieces 



