6oo 



NORTH AMERICAN INDEX FOSSILS. 



46. H. texanus Roemer. (Fig. 1934, /-/^.) Cretacic. 

 Anterior groove broad and deep. Anterolateral ambulacra bent 



backward in upper portion. Mouth opening large, transversely 

 oval. Anal opening large, oval, at center of truncated posterior 

 surface. 



Characteristic of the Austin (Niobrara) of Texas. 



47. H. lacunosus Slocum. (Fig. 1935.) Cretacic. 

 Differs from H. parastatus in its smaller size and in the pres- 

 ence of sunken areoles around the tubercles; posterior interambu- 

 lacral area rounded. 



Ripleyan of Mississippi. 



Fig. 1934. a-e, Hemiaster parastatus^ lower, lateral, upper and posterior views, 

 X %> and adoral area enlarged ; f-h, H. texanus, lower, upper and lateral views, 

 X %. (After Clark.) 



48. H. parastatus (Morton). (Fig. 1934, a-^.) Cretacic. 



Upper surface elevated, with a deep anterior groove and a sharp 

 posterior ridge, the latter truncated by the flat, nearly vertical 

 posterior margin. Petaloid areas depressed, anterior pair bent 

 backward at their center and about twice the length of the pos- 

 terior. Mouth opening with distinct overhanging lip. Anal open- 

 ing small, situated high on the truncated posterior surface. 



Ripleyan of Alabama and Mississippi; Jerseyan of New Jersey 

 (Vincentown). 



