108 University of Texas Bulletin 



marine Cretaceous in Texas" (Buda limestone?) and is "not as Dr. 

 Roemer infers from the specimens which accompanied it to Germany : 

 with the Exogyra texana fauna, a statement which has been verified by 

 Mr. George Stolley, the collector." 



The distinction between Hemiaster and Epiaster revolves around the 

 presence or absence of fascicles, and Clark' refers Epiaster elegans Auctt. 

 to the genus Hemiaster "as better material has shown that peripetalous 

 fascicles are present although poorly developed and commonly destroyed 

 on most specimens." There seems no a priori reason for doubting this 

 statement until well preserved material demonstrates the contrary. 



Epiaster aguilerae Bose, 2 a distinctive species of the lower Fort Worth 

 limestone, described from subdivision 5 of Cerro de Muleros near El Paso, 

 is here redescribed by comparison with E. wenoensis n. sp., an analagous 

 a'nd equally distinct species from the Upper Washita beds of North Texas. 

 In the collections of the Department of Geology, University of Texas, is an 

 unlabeled echinoid, probably an Epiaster wenoensis, and marked with 

 a red T, as many of Cragin's types were marked, but whether this is a 

 type, and of what, is unknown. Its dimensions, length 36.5 mm., breadth 

 34.0 mm., height 17.0 mm., do not agree with those of any Epiaster men- 

 tioned by Cragin, who described Epiaster electus (Travis Peak forma- 

 tion), E. elegans var. praenuntius (Comanche Peak limestone), E. hem- 

 iasterinus (Grayson formation), and E. whitei Clark (Travis Peak, 

 Comanche Peak and Fort Worth formations). Since Cragin's species are 

 unfigured and the types apparently lost, they are considered invalid species. 

 The present species differs from Hemiaster whitei Clark in being much 

 less tuberculate, in having narrow straight ambulacra in shallow grooves 

 instead of wide ambulacra in deep grooves ; the form is much wider, more 

 broadly rounded posteriorly, and distinctly lower; the slope anterior to 

 the apical system is steeper. In appearance this species can not be con- 

 fused with the common H. whitei Clark of the North Texas Goodland lime- 

 stone. Epiaster hemiasterinus Cragin is considered by Clark 3 as identical 

 with Hemiaster whitei, and Cragin admits 4 the "probable identity" of the 

 two. It is described as being tall, with deep ambulacral grooves. 



iClark and Twitchell, U. S. G. S. Mon. LIV, p. 88, 1916. 



2 B6se, Inst. Geol. Hex., Bol. 25, .p. 173, pi. 47, figs. 2-4, 67; pi. 48, figs. 1, 2, 4, 1910 



3 Clark, U. S. G. S., Mon. LIV, p. 89, 1915. 



4 Cragin, Geol. Surv. Texas, 4th Ann. Kept., p. 155, 1893. 



