NO. 4 ECHINOIDS, TRINIDAD AND VENEZUELA — COOKE 9 



Figured specimen. — USNM 131 168. 



Comparison. — Hemiaster sp., known only from two specimens, one 

 very much corroded, is most closely related to Hemiaster calvini Clark 

 (Cooke, 1946, p. 225, pi, 32, fig. 5) from the Washita group of Texas ; 

 but it is lower, its petals are shallower, and its posterior truncation 

 slopes less steeply. 



EPIASTER WHITEI Clark 

 PI. 2, figs. 6-9 



Epiaster ivhitci Clark, 1891, Johns Hopkins Univ. Circ, vol. 10, No. 87, p. 77. 

 Epiastcr whitei Clark. Clark, 1893, U. S. Geol. Surv. Bull. 97, p. 82, pi. 43, figs. 



2a-d; pi. 44, figs. la-g. 

 Hemiaster whitei (Clark) (part). Gark, 1915, U. S. Geol. Surv. Monogr. 54, 



p. 89, pi. 43, figs. 2a-c; pi. 44, figs. la-h. Not pi. 45, figs. la-c (type of 



Mac raster zvashita Lambert). 

 Hemiaster li'hitci (Clark). Cooke, 1946, Journ. Paleont., vol. 20, No. 3, p. 224, 



pi. 32, figs. 16-17. Includes additional synonymy. 

 Epiaster whitei Clark. Cooke, 1955, U. S. Geol. Surv. Prof. Pap. 264-E, p. 108. 



Cordate, with a shallow depression in front and a narrow vertical 

 truncation behind ; moderately inflated, margin rounded ; highest point 

 at the apical system, evenly rounded in front, gently sloping behind 

 to the truncation ; widest at the anterior third ; sides evenly rounded 

 to the anterior depression, straighter behind. Apical system slightly 

 anterior ; ethmophractic, the two posterior genital plates touching, the 

 madreporite not protruding between them ; four genital pores, nearly 

 equally spaced. Anterior ambulacrum depressed ; pores short, outer 

 pores transverse, inner pores diagonal except near the apical system, 

 where they are transverse. Paired petals depressed, moderately long, 

 the anterior pair the longer; pores elongated, parallel ; interporiferous 

 zones nearly as wide as the poriferous. Peristome far forward, sub- 

 pentagonal, small. Periproct small, higher than wide, near the top of 

 the vertical truncation, barely visible from above. Tubercles widely 

 scattered, larger on the under side. 



Length of holotype 40 mm. ; width 35 mm. ; height 23 mm. 



Well-preserved specimens show a fine granulation, which is par- 

 ticularly noticeable in a broad band surrounding the ends of the petals, 

 but there is no fasciole. This granulation is not preserved on the holo- 

 type (the locality of which is unknown), but it shows traces of a 

 narrow smooth area suggestive of a peripetalous fasciole. 



The preceding description is based on the holotype and other, 

 better-preserved specimens from Texas. The figured specimen from 

 Venezuela is more compressed posteriorly and is somewhat shorter 



