84 MESOZOIC ECHINODERMATA OF THE UNITED STATES. [bull. 97. 



zones far ai)art, and the pores small and approximated (PI. XL,v,Fig. 1/). 



The surface is covered with small tubercles, between which are nu- 

 merous microscopic grauules (PI. xlv, Figs. 1/, Ig, li, 11, and Im). 



The apical disk is small and situated posteriorly to the center of the 

 upper surface. The four genital plates are distinctly perforated and 

 separated by the five small oculars (PI. xlv, Fig. In). 



The mouth opening is transversely arched and bilabiate. The lower 

 lip projects prominently. The anal opening is small ami situated high 

 on the truncated surface of the posterior margin. The j)eripetalous 

 fascioleis broad and distinct (PI. xlv. Figs, li, 1^). 



Belated forms. — Hemiaster parastatan is most closely related to H. 

 ungula, from Avhich, however, it is separated by its deei)er and broader 

 anterior sulcus, more i)osterior position of the apical disk, and more 

 inflated sides. It is apparently distinct from any of the many species 

 described from European deposits. 



Locality and geological horizon. — H. parastatus is from the yello^Mjlime- 

 stone of the middle marl bed (upper Cretaceous) of Timber creek, 

 New Jersey, and also from the Ripley group (upper Cretaceous) of 

 Alabama. 



Collections. — Philadeli)hia Academy of Natural Sciences; American 

 Museum of Natural History, New York ; Johns Hopkins University. 



HEMIASTEli Desor. 



Hemiaster stella (Morton). 



Plate XL VI, Figs, lor-d. 



Spatangns steVa Morton, 1830. Am. Jonr. Sci., Ist ser., vol. 18, p. 24.5, PI. 3, Fig. 11. 

 Spatanguts steUa Morton, 1830. rhiladelphiii Acad. Nat. Sci. Jour., 1st ser., vol. 6, p. 



200. 

 Spatangus Stella Morton, 1834. Synop. Organ. Remains Cretaceous, j). 78, PI. 3, Fig. 18. 

 Hemiaster slella Agassiz and Desor, 1847. Cat. rais., i». 141. 

 Hemiaster stella Desor, 1858. Synop. des Ecliinides ibssiles, p. 373. 

 Hemiaster stella Gabb, 1859. Cat. Invert. Fossils, Cretaceous, p. 19. 

 Hemiaster {?) stella Meek, 1864. Smith Misc. Coll., vol. 7 (177), p. 3. 

 Hemiaster Wetherbyi de Loriol, 1887. Recueil Zoologique Suisse, f. 4, jip. 391^394, PI. 



17, Figs. 5-8. 

 Hemiaster incrasaatus Clark, 1891. Johns Hopkins University Circulars, No. 87, p. 77. 



Determinative characters. — Test small, oval, cordate, inflated, rounded 

 before, truncated behind; upjier surface elevated posteriorly, sloping 

 anteriorly; anterior groove short, not reaching the ambitus. Ambula- 

 cra straight, depressed above. Apical disk exceutric and jjosterior. 

 Mouth opening bilabiate and near the anterior border. Anal ojiening 

 small, high above posterior margin. Fasciole distinct. 



Dimensions. — Length, 1 inch; width, 1 inch; height, f inch. 



Description. — This form Avas originally described by Morton in 1830, 

 and later, in 1833, considered by the same writer as the young of 

 the species for which the name parastatus was then substituted. In 

 presenting a preliminary notice of the x)resent rex)ort the writer followed 



