302 CRETACEOUS PALEONTOLOGY. 



greatly elevated posteriorly, sloping rapidly to the front, with a 

 narrow and deep anterior sulcus and a sharp ridge at the posterior 

 median line terminated by the nearly vertical truncation of the 

 posterior side, lateral and anterior sides rounded. Ambulacral 

 areas petaloid, narrow, the petaliferous portion straight and 

 deeply impressed, the antero-lateral pair twice as long as the 

 postero-lateral ones ; the pores of the paired ambulacra elongated 

 and separated, those of the single ambulacra small, oval and ap- 

 proximated. Interambulacral areas broad, composed of large 

 plates. Surface of the test covered with small tubercles, between 

 which are numerous minute granules; the peripetalous fasciole 

 distinct and bent strongly inward between the anterior and pos- 

 terior-paired ambulacra. Apical disk small, situated posterior to 

 the center of the dorsal surface and anterior to the point of great- 

 est elevation of the test; the antero-lateral genital plate very 

 large and widely separating the posterior pair of oculars, the 

 postero-lateral genitals with large perforations. Oral opening 

 transversely subelliptical, bilabiate, with a prominently projecting 

 lower lip. Anal opening large, situated at the upper part of the 

 truncated face of the posterior margin. 



The dimensions of a complete example are : length, 31.25 mm. ; 

 width, 28 mm. ; height, 21.9 mm. 



Remarks. — This species may be easily distinguished from H. 

 parastatus by its narrower anterior sulcus, its more nearly cen- 

 tral apical disk, its sharper posterior keel, its straight ambulacral 

 areas, and by its more deeply incurved peripetalous fasciole 

 between the paired ambulacra. 



Formation and locality. — -Vincentown limesand, Timber Creek 

 (Clark). 



Geographic distribution — New Jersey. 



Hemiaster welleri n. sp. Clark. 

 Plate XVII., Pigs. 4-6. 



Description. — Test cordiform, inflated, dorsal surface only 

 slightly elevated posteriorly, ventral surface flat, sides rounded. 

 Anterior sulcus broad and clearly defined, not deeply indenting 

 the anterior ambitus ; the posterior ridge not greatly accentuated. 



