244 Systematic Paleoxtology 



The foiir following specimens represent four stages in the growth of this 



specimen 1 . 

 Specimen 2 . 

 Specimcn'^3 . 

 Specimen"4 . 



[jength 



24 mm. 

 35 mm. 

 57 mm. 



Width Depth Brachioles (total) 



Itmm. 9 mm. 



17 mm. 12 mm. 

 27 mm. 15 mm. 

 39 mm. i?20mm. 



20 flichop. 

 42 (lichop. 

 53 dichop. 

 82 dichop. 



34 dichop. 



48 dicliop. 

 65 dichop. 

 114 dichop. 



Rhomb 14-15 



40 dichop. 

 58 dichop. 

 82 dichop. 

 148 dichop. 



Occurrence. — iHelderbeeg FoRMAXioisr, Keyser Member. Keyser, 



Virginia. 

 Collection- -Tj. S. Xational Museum. 



Genus TRIMEROCYSTIS Schuchert 



Trimerocystis peculiaeis Schuchert 



Plate XXXIV, Figs. 8-10 



Trimerocystis peculiaris Schuchert, 1904, Smith. Misc. Col., vol. xlvii, pt. ii, 

 pp. 239, 240, pi. XXXV, figs. 1-3; text fig. 34. 



Description. — Ambulacra prominent, rounded, extending along three 

 sides, bent around the excavated base of the theca, and touching the 



Fig. 13. — Analysis of Trimerocystis peculiaris Schuchert. 



column. Each ambulacrum has on one side about 30 brachioles, or 60 to 

 each ray, and about 180 on the entire theca. Brachioles apparently not 

 very stout nor long, and composed of rather large pieces. Ambulacral 

 grooves narrow, but deep, and covered by a series of small ambulacralia 

 arranged much as in Pseudocriniies perdetvi, with the pieces somewhat 

 larger. 



