192 THE CEINOIDEA CAMERATA OF NORTH AMERICA. 



founded. Through the kindness of Prof. Whitfield we were permitted to 

 examine this specimen, and to free it from the surrounding matrix, when we 

 found the pinnules well developed, and the plates of the calyx arranged as 

 in the typical form of Thjsanocrinus (Plate XVIII. Fig, 4). 



Eucrijius was separated from Thysanocrinus on account of having twenty 

 arms, as against ten in the latter. A bifurcation or two, more or less, cannot 

 be regarded as a good generic distinction, and we therefore place Angelin's 

 species : Eucrinus interradialis, E. Icevis, E. ornatiis, E. quinqua7igularis and 

 E. speciosus,\mdQv Thysanocrinus ; but not his E. minor or E. venustus^ which 

 are types of a different genus. Rhodocrinus quincjuelobiis Schultze, which we 

 formerly placed under Eucrinus, is a Rhodocrinoid. Thjsanocrinus {Rhodo- 

 crinus) microlasilis, and Th. {Rhodocrinus) pyriformis Billings, have been re- 

 ferred by us to Archwocrinus ; Th. immaturus to Idiocrinus. Thysanocrinus 

 acideatus and Th. canalicidatus are named from arm fragments. Dimerocrinus 

 oligoptilis, and its synonym D. ajotilis from Russia, belong to Taxocrinus. 

 Glyptaster pentangidaris Hall is described from internal casts, and is, to say 

 the least, a doubtful species. Cyathocrinus icaldronensis S. A. Miller {Dimero- 

 crinus lualdronensis W. and Sp.) cannot be identified fi'om the description and 

 figure, but may be a young Thysanocrinus inornatus. Neither can Glyptaster 

 Egani S. A. Miller, which is described from a fragmentary specimen. 



Thysanocrinus liliiformis Hall. 

 Plate XVIII. Fig, Jf. 



1852. Thysanocrinus liliiformis — 11a~ll\ Palseont. N. York, Vol. H., p. 188, Figs. la-f. 



1881. Dimerocrinus liliiformis — ISf. and Sp. ; Revision Palseocr., Part XL, p. 199, and Proceed. Acad. Nat. 



Sci. Phila., p. 373. 

 1889. Thjsanocrinus liliiformis — S. A. Miller; N. Amer. Geo], and Palseont., p. 286. 



■9 



Form of calyx apparently globose (the exact shape cannot be ascertained 

 owing to the somewhat crushed condition of the type specimen) ; the plates 

 ornamented by elongate nodes or interrupted strise, which give to the surface 

 a corrugated appearance. 



Infrabasals small, scarcely visible in a side view. Basals nearly as large 

 as the radials • that of the anal side even larger and broadly truncate, the 

 others angular above. All plates in a radial direction provided with a low, 

 almost flat, obscure ridge, following the median line of the plates, and 

 covered by longitudinal striae which are continued into the arms. Radials 

 wider than long, but slightly angular below; their lateral faces short, leaving 



