92 SMITHSONIAN INSTITUTION 



prevails universally among the Recent crinoids. Upon this ground it was 

 formerly held by myself as well as others, and perhaps may still be held by 

 some, that the comatulids and some of the Recent groups should be considered 

 as a pinnulate division of the Flexibilia. My reasons for no longer adhering 

 to this view have been stated in the revised edition of the Zittel-Eastman 

 Paleontology, 1913, p. 227, and will be further discussed in the chapter on 

 Classification. 



Dr. G. Steinmann 1 in a general discussion of evolutionary principles has 

 expressed a very positive opinion that the Jurassic Apiocrinidae are descended 

 from the Paleozoic Flexibilia, contending that it is even possible to derive some 

 Apiocrinidae from particular species of Flexibilia. He undertakes to trace the 

 connection through the genus Guettardicriiuis and Forbesiocrimis greenei 

 M. and G. 2 from the Lower Carboniferous, and for the latter proposes a new 

 genus, Proguettardicrinus. This is done purely on the ground of superficial 

 resemblance and minor characters such as the number of brachials, while 

 overlooking the broader characters such as bilateral symmetry produced by 

 anal structures, regularly arranged interradials, loose sutures uniting the calyx 

 plates of this and a closely related species, which decisively establish the posi- 

 tion of this form under Forbesiocrimis. Some of these characters were not 

 clearly shown by the original figure and description, but they may all be seen 

 in full detail upon Plates XXX and XXXI of this work. 



Steinmann admits that with the nonexistence of pinnules in the Flexibilia 

 established, the chasm between the Flexibilia and the Apiocrinidae cannot be 

 bridged; but he avoids this difficulty by assuming that in the older forms the 

 pinnules were soft structures and therefore not preserved, while later under 

 different physical conditions they became solidified by lime deposit. This is 

 pure hypothetical invention, without proof or probability, but directly contrary 

 to the fact that in the two other Paleozoic groups, existing under the same con- 

 ditions and found in the same formations as the Flexibilia, calcareous pinnules 

 are profusely developed. There are unquestionably strong points of similarity 

 between the Apiocrinidae and some Paleozoic Flexibilia, to which perhaps 

 more than anything else was due the opinion of Wachsmuth and myself con- 

 necting" that family, as Bather now does, with this order under the Grade Flexi- 

 bilia Pinnata. According to my present views, the presence in the Apiocrinidae 

 of pinnules and of a terminal stem plate, the irregular interradials when pres- 

 ent, the absence of a flexible calyx structure, and the admitted impossibility of 

 tracing any line of connection with the Paleozoic Flexibilia, combine to furnish 

 sufficient grounds for ranking them under the Articulata as now defined. 



1 Die geologischen Grundlagen der Abstammungslehre, 1908, p. 152. 

 * Illinois St. Mus. Nat. Hist., Bull. 9, 1896, p. 57, pi. 4, figs. 1, 2. 



