NO. 3 ON THE FOSSIL CRINOID FAMILY CATILLOCRINIDAE 7 



In addition to Schultze's type, another species, M. gramdatiis, has 

 been described by Jaekel, on account of its granular surface; and a 

 third, M. conicus, is herein proposed because of its conical, instead of 

 knob like, base. In both of these the base appears undivided, except 

 for one faint suture in the latter. 



CHANGES TOWARD CATILLOCRINUS 



The change in calyx structure which took place from Mycocrlnus 

 to Catillocriniis consisted chiefly in the reduction of the high, massive, 

 protruding basal knob to a relatively low, and in the typical species 

 exceedingly thin, disk; and in the shape and proportions of the radial 

 plates by which, except in one species, the two larger ones became 

 relatively much wider above, at the expense of the three smaller ones, 

 in two of which the upper face was reduced to a narrow apex. These 

 plates also became bounded by curved lines, except some of those 

 bounding the smaller pair which remained straight. In the last 

 survivor of the degenerative series, C. carpenteri of the Chester, 

 there is a tendency to return to the earlier plan ; the three smaller 

 radials fill nearly half the circumference of the cup. and their lines 

 are mostly straight. 



The thinness of the base, in contrast with its massiveness in Myco- 

 crlnus, is most remarkable, and almost without a precedent among 

 the crinoids. In the type species, C. tcnnesseeae, it is as thin as fine 

 writing paper, and translucent, so that in some specimens the outline 

 of the infrabasal ring, to be presently described, can be seen by trans- 

 mitted light. 



In this genus we first become acquainted with the actual structure 

 of the slender arms, and of the relatively enormous anal tube, neither 

 of which, however, were known to the earliest describers, nor in their 

 full details until now. 



CATILLOCRINUS (Troost) Shumard 



Shumard, Catal. Pal. Foss, 1866, p. 2i57 



Shumard's generic diagnosis is as follows : 



Catillocrinus Troost, 1850 



List, Crin. Tenn. Proc. Am. Assn. Camb. Meeting, p. 60 



Generic character. Basal pieces 5, small, forming' together a low cone. 

 Primary radials 5? Secondary radials 5, very irregular in form, two of them 

 large, transverse, somewhat lozenge-shaped ; two subquadrangular, one lance- 

 olate; their superior edges broad, and marked with strong, radiating, curved 



