NIAGARA FALLS AND VICINITY 



159 



Order f^lexibilia. Zittel 

 Genus ichthyocrinus Conrad 



[Ety.: txOo^, fish; -/.f)CM)v, lily] 



(1842. Acad. iiat. sci. FJiil. Jour. 8:279) 



Calyx with all plates above the radials united by loose suture or 

 by muscular articulation. Base dicyclic ; infrabasals three, unequal, 

 very small, rarely extending beyond the top stem joint with which 

 they are fused. Basals five, small. Radials and lower brachials 

 laterally in contact on all sides; no interradials or anals. Brachials 

 united by more or less wavy sutures and their lower edges furnished 

 with tooth-like projections which fit into depressions on the sub- 

 jacent plates. Tegmen squamous, composed of five orals and 

 numerous, very small, movable plates. Arms non-pinnulate, with 

 a wide, shallow ventral groove. When the arms are folded, the 

 crown appears like a perfectly solid body. Stem round, the upper 

 joints extremely short, and generally wider than the others. 



Ichthyocrinus laevis Conrad (Fig. 54) (Hall. 1852. Pal. N'. Y. 

 2:195, pi. 43) 



Distinguishing characters. Stem slender, round and smooth, grad- 

 ually enlarging to the base of the calyx 

 and composed of alternate thick and thin 

 joints; radials five, succeeded by two to 

 four costals in each radius; 10 columns of 

 distichals, from six to nine plates in each, 

 an unequal number in the two columns 

 of each radius; 20 columns of palmars, 

 and 40 of post-palmars, the number of 

 plates varying in the columns of the same 

 individual; plates with lower margins ob- 

 tusely triangular and upper margins with 

 a corresponding reentrant angle; axillary 

 plates angular above and below. 



Found in certain calcareous layers near the middle of the lower 

 Rochester shales at Niagara. Also in the same shales at Lockport 

 (Hall). 



Fig. 54 Ichthyocrinus laevis with 

 stem enlarged 



