278 



Field Columbian Museum — Geology, Vol. II. 



DESCRIPTION OF GENERA AND SPECIES. 



Order I. LARVIFORMIA. 



Family PISOCRINID^. 



PISOCRINUS De Konik. 



No members of this genus have hitherto been reported from this 

 Area. Representatives of three species, P. benedicti, P. gemmiformis 

 and P. qainquelobus were found by the writer. The generic characters 



are as follows: Calvx small, 

 ill 





Fig. 3. Diagram of Pisocrinus. (After Bather). 



globular, subconical or sub- 

 cylindrical. Facets for the 

 attachment of the arms wide, 

 angular and projecting limbs 

 of the radials short. 



Basals five, forming a tri- 

 angle. The three plates sit- 

 uated at the angles larger 

 than the other two. Radials 

 five, extremely irregular, only the left posterior and anterior radials 

 in contact with the basals. These are more than twice the size of the 

 other radials. The left anterior radial is angular below, resting on the 

 lateral edges of the two large radials. The right posterior and right 

 anterior radials rest upon a large inferradial which separates them from 

 the basal plates. Notwithstanding the great difference in size of the 

 radials, their distal edges are about equal. Anal plate rests on the 

 processes of the posterior radials. 



Arms neither branched nor pinnulate. 



Pisocrinus gemmiformis S. A. Miller, Plate LXXXIV, Figs. 1-4. 

 1879. P. gemmiformis S. A. M., Jour.. Cincin. Soc. Nat. Hist. 



Vol. 2, p. 113, PI. 9, Figs. 6 a-c, Osgood, Ind. 

 1886. P. gemmiformis Wachsmuth & Springer, Rev. Palaeocr. 



Pt. Ill, p. 184. 

 1892. P. gemmiformis S. A. M., 17th Rept. Geol. Surv. Ind. 



p. 636, PI. VI, Figs. 10-12, Madison, Ind. 

 Calyx globular, depressed at the base: plates thick, sutures in- 

 distinct, surface smooth or finely granular. 



Basal plates five, forming a nearly equilateral triangle and curving 



