292 Field Columbian Museum — Geology, Vol. II. 



Locality: Collected by the writer in the spoil heaps along the 

 Chicago Drainage Canal about 1 ]/ 2 miles east of Lemont, Illinois. (Mus. 

 No. P 8887.) 



Family CROTALOCRINID^. 



CROTALOCRINUS Austin. 

 Crotalocrinus cora Hall, Plate LXXXVI, Figs. 3 and 4. 



1868 Cyathocrinus cora Hall, 20th Rept. N. Y. St. Mus., p. 324, PI. 



XI, Figs. 13, 14. 

 1870 Cyathocrinus cora Hall, 20th Rept. N. Y. St. Mus. (Rev. 



Ed.), p. 366, PI. XI, Figs. 13, 14. 

 1879 Cyathocrinus cora W. & Sp., Rev. Paleocrin., Pt. I, p. 85. 

 1881 Cyathocrinus cora S. A. M., Jour. Cin. Soc. Nat. Hist., Vol. 



IV, p. 171. 

 1900 Cyathocrinus cora Weller, Bull. 4, Nat. Hist. Surv. Chicago 



Acad. Sci., p. 62, PI. XIV, Figs. 6-10. 

 1900 Crotalocrinus americanus Weller, ibid. p. 143, PI. XIV, Fig. 1. 

 1902 Crotalocrinus cora Weller, Jour. Geol., Vol. X, p. 532, PI. III. 

 This species is abundant at various localities in the vicinity of 

 Chicago and at Racine, Wisconsin, in the form of natural casts, but it 

 is rarely found with the brachial plates preserved. The specimen here 

 figured (Mus. No. P 8809) shows the anterior and right anterior rays, 

 complete to the fourth bifurcation of the brachials, and part of the left 

 anterior and right posterior rays. This is probably the most complete 

 specimen of this species yet discovered. The specimen consists of a nat- 

 ural cast with more than half the accompanying mold. Fig. 3 is drawn 

 from a "composition" impression taken from the natural mold. Col- 

 lected by the writer in the upper layers of the Hawthorne Quarry, Chi- 

 cago, May, 1906. 



Order III. CAMERATA. 

 Family PLATYCRINID^. 



■ PLATYCRINUS Miller. 

 Platycrinus augusta sp. nov. Plate LXXXVI, Figures 5-7. 



Dorsal cup subhemispherical, sharply constricted above, with the 

 base produced into a circular facet for the attachment of the column. 

 Pentangular in transverse section at the arm bases, circular below. 

 Plates thin, without ornamentation, conforming to the curvature of 

 the calyx; sutures not in furrows, inconspicuous. 



