251' DE. r. A, BATHER ON TKIAS'SIC [vol. Ixxiii. 



rounded star, with diameter = 2"85 inin. (the text says 5 to 2 inm.) 

 and height =0*8 mm. (the text ssijs 0'33 to 1 mm.), llatio of 

 height to diameter = 0-28 (the text would make it OQ to 0*5 ). 

 The lumen is said to be ' small,' but as drawn has ai diameter of 

 0"35 mm. No other characters of the joint-face are either figured 

 or described, although the drawing suggests that the side-faces 

 Avere transversely ridged. This feature and the general outline 

 distinguish I. smitlii from I. treclimanni. 



Isocriniis calif orniciis, from the Upper Trias, is represented b}^ 

 well-preserved columnals. The section as drawn is a rounded star, 

 Avith a diameter- = 8-75 mm. (the text says 2 to 5 mm.) ; height = 

 nearly 0*8 mm. (the text says 0*5 to 1 mm.). Ratio of height 

 "to diameter = from about U"25 to 0*2. The lumen is said to be 

 'large and well-marked.' but as drawn has a diameter of 0'14mm., 

 which (as compared with I. smithi) Avould be even minute. The 

 petals are ' narrow ' and ' sharply terminated ' ; from the drawing 

 it appears that the ridges are short and not confluent at the peri- 

 phery, but the side-view shows no trace of crenellae, which is 

 curious. The side-faces appear from both drawing and photograph 

 to be gently convex at the IR angles and sharply so at the 

 reentrant r angles, so that in the angle the sides are transversety 

 ridged. The photograph shows rather clearly a cirral, with section 

 circular, joint-face rimmed, central area raised, lumen minute. 

 The scalariform sides of I. californicus are enough to distinguish 

 it from I. treclimanni, whatever its other characters may really 

 be. 



Tiie third species is a form recorded in 1877 by Hall &• Whit- 

 field ^ from limestone of Middle Triassic age in Nevada. They 

 referred it with doubt to the Jurassic Fenfacrimis asferiscus 

 Meek & Hayden. That, however, appears to be a Pentacrimis 

 sensu stricto, Avhereas the Triassic species is rightly referred by 

 Prof. Clark to Isocrinus. Unfortunately, he neither describes nor 

 names it. The specimen is said by him, as formerly by Whitfield 

 in his ' List of Types,' to be in the U.S. National Museum ; but 

 Dr. Bassler, who has kindly searched, tells me that it cannot now 

 be found. The original figure, howcA^er, is quite clear enough to 

 serve as the basis of a diagnosis and a name. The following are 

 therefore submitted : — 



Isocrinus argenteus, sp. nov. Transverse section a slightly 

 rounded star. Joint-face Avith radial triangle; lumen relatively 

 large and quinquelobate Avith radial lobes ; petals lanceolate, but 

 not narrow ; radial ridge-groups about 3, remainder of ridges about 

 15, but of these only 2 or 3 at the distal end of the petal reach 

 the peripheiy. Diameter, may 'exceed one-fourth of an inch' 

 (say 7 mm.). 



Holotvpe. — The specimen figured as Penfacrinites asferiscus? 

 by Hair& Whitfield, 1877. 



1 U.S. Geol. Explor. 40th Parall., Final Eep. vol. iv, p. 280 & pi. vi, fig-. 16. 



