MO. 3 ON THE FOSSIL CRINOID FAMILY CATILLOCRINIDAE I5 



toward the structure of the Devonian form, as in the rectangular 

 shape of the smaller radials, but to the flat and extremely low base of 

 C. tennesseeae. 



ASYMMETRY OF RADIALS 



The extreme disproportion in size of the radials in the type species 

 of this genus is accompanied by a further asymmetry, unusual in the 

 crinoids, due to the fact that the basal ring, most of which is covered 

 by the column, projects more or less beyond the column at the anterior 

 side, while at the opposite side it is either invisible or reduced to a 

 narrow band. Also the radials toward the anterior side are somewhat 

 higher than those opposite to them, so that the dorsal cup stands 

 slightly oblique to the vertical axis of the column. This obliquity is 

 more pronounced (but in the reverse direction) in the Timor form. 

 In some of the later crinoids it becomes a very marked feature in 

 their structure, e. g., Cyrtocrinus niutans and others figured by Jaekel 

 in 1907 (Korperform der Holopocriniten, p. 279, et. seq.). When 

 carried to an extreme, this would result in the complete bending of 

 the calyx to a pendent position, as in the Cremacrinidae. Excep- 

 tionally the projection of the basal ring is at the posterior side (2 

 out of a dozen specimens in C. tennesseeae, but none in 8 specimens 

 of C. wachsmuthi) , which Wanner finds to be the rule in the Timor 

 form, or as he states it the projection is least under 1. ant. R. In the 

 later American species, with the increase in height of the basal ring 

 the difference in its projection becomes less. 



In connection wdth the asymmetric proportions of the radials, it 

 results that in the Catillocrinidae the cup is usually elliptic in outline, 

 instead of circular as in most other crinoids. The long diameter 

 bisects the two larger radials. This character is conspicuous in C. 

 tennesseeae, the difference between the short and long diameter in 

 an average of 14 specimens being about as i to 1.12; it prevails 

 more or less throughout all the species, but least of all in C. carpenteri 

 and in Mycocrinus eonicus. In comparative measurements of the 

 cup in different specimens, if only one figure is stated it means the 

 long diameter. 



The asymmetry of the cup in Catillocrinus goes so far that even the 

 two larger radials are not equal. With but few exceptions, the ante- 

 rior radial is wider at the upper margin than the opposite left posterior, 

 and has a greater number of food grooves. The difference varies 

 in the different species, the proportion in width of 1. post R. to ant. 

 R. being on an average from i to 1.24 minimum to i to 1.50 maximum 

 in C. tennesseeae, turhinatus, wachsnmthi, and shumardi; while in 



