236 



ECHINODERMATA— PELMATOZOA 



PHYLUM IV 



Fig. 339. 



Uiiitaerinus westplialiciis (Schliit.). Upper Cretaceous ; Reck- 

 lingshausen, Westphalia, a, Calyx viewed from the side ; h, 

 Inferior aspect. Natural size (after Schliiter). 



Represented by a single genus, Uintacrinus Grinnell (Fig. 339), occurring 

 in the Upper Cretaceous of Western America (especially Kansas), England 



and Westphalia. In the latter 

 areas it is widely distributed, 

 accompanied by Marsupites 

 and B our gueticr inns. In the 

 Kansas region it is found ex- 

 clusively in colonies which 

 had been herding together in 

 \/ deep water. The genus in its 

 calyx structure is a survival 

 of the Flexibilia plan ; it is 

 strongly in contrast with 

 Marsupites in this, and in the 

 length of the arms, which in 

 mature specimens attained a 

 length of four feet, giving 

 when outstretched a spread of upwards of eight feet, the largest known 

 Crinoid. 



Tribe 2. Oligophreata A. H. Clark. 



Bottom-inhabiting Comaiulids, stalked when young; basals metamorphosed into 

 a rosette ; infrabasals unknown ; cavity in the centrodorsal containing the chambered 

 organ, and overlying structures very small, these being pushed up more or less within 

 the radial circlet ; disk more or less studded, or even completely covered, with large 

 calcareous concretions or plates: pinnules, at least the lower, wholly or in part 

 prismatic, and composed of short segments ; usually more than ten in number. 



Generic names have been applied to fossil Comatulids belonging to this 

 division, but the specimens upon which they are based are rarely well enough 

 preserved to admit of correlation with generic names based upon Recent types. 

 The latter include a surprisingly large number of living genera, which are 

 grouped by A. H. Clark in nearly a dozen different families. Among these 

 may be mentioned the Comasteridae, Zygometridae, Thalassometridae and 

 Charitometridae as examples. 



Tribe 3. Macrophreata A. H. Clark. 



Bottom-inhabiting Comatulids, stalked lohen young ; basals usually metamorphosed 

 into a rosette ; infrabasals, three, or more usually five, in number, have been detected 

 in the young of several species, where they fuse with the centrodorsal ; cavity in the 

 centrodorsal containing the chambered organ and associated structures large ; tegmen 

 naked, or studded with minute plates which may become grouped in the interradial 

 angles, particularly between the IBr ; pinnules all cylindrical or more or less 

 flattened, slender, with very long joints ; arms five or ten in number, except in the 

 genera in which there are ten radials, in which they may he twenty. 



Within this category are embraced three divisions — Atelecrinidae (Bather), 

 Pentametracrinidae (Clark) and Antedonidae (Norman) — the last-named of 

 which is again divided into a number of groups having the rank of sub- 

 families. One of them, Antedoninae, includes the Recent genera Antedon 



