ECHINODERMATA—CRINOIDEA. 



long and slender. Surface nearly smooth. 

 Trenton of Ottawa. 



563 

 Column pentangular. 



LXXII. IcHTHYOCRiNUS Courad. 

 General form, including arms, ovoid to pear-shaped. Calyx 

 cup-shaped ; all the plates above the R united by loose sutures or 

 by muscular articulation, producing flexi- 

 bility. IB 3, very small, rarely extending 

 beyond the top stem joint with which they 

 are fused. B 5, small. R and lower 

 brachials laterally in contact on all sides. 

 No IR or anals present. Brachials united 

 by more or less wavy sutures and their 

 lower edges furnished with tooth-like pro- 

 jections which fit into depressions on the un- 

 derlying plates. Tegmen scaly, composed of five orals and numerous 

 very small, movable plates. Arms nonpinnulate, 20-60 or more, 

 infolding at their tips. Crown appearing like a perfectly solid body 



\ 



Fig. 



Ichthyocrinus. 



( After Weller. 



Fig. 19CX). Ichthyocrinus Icevis, with Fig. 1901. Lecanocrinus macropetalus. 

 enlargement of stem. (After Hall.) (After Hall.) 



when the arms are folded. Stem round, the upper joints extremely 

 short and usually wider than the others. Usually to be recognized 

 by its symmetrical, equilateral form. (Fig. 1899.) Siluric. 



