ECHINODERMATA. 297 



Description. Test distinctly cordate, with a pronounced sul- 

 cus anteriorly occupied by the anterior ambulacral area, the pos- 

 terior extremity somewhat pointed; the lower surface nearly 

 flat except for the slight depression towards the margins of the 

 oral opening, and a rounded, ridge-like elevation extending from 

 the center to the posterior margin; dorsal surface convex, 

 curving downward to the ambitus which is near the base, the 

 regular curvature of the surface interrupted by the strong an- 

 terior sulcus and by a slight ill-defined ridge which passes pos- 

 teriorly from the apical disk to the vertically truncated surface 

 of the posterior margin. Ambulacral areas broad, not petaloid, 

 separated at the apex; the a'ntero-lateral pair curving slightly 

 forward and the postero-lateral pair slightly backward in their 

 proximal portion, beyond which they extend straight to the 

 margin; the unpaired anterior ambulacrum occupying the deep 

 anterior sulcus ; the pores of the paired ambulacra consist, in the 

 upper portion of the series, oi oblique oval openings united by 

 furrows, while lower down they become small and indistinct; 

 in the anterior ambulacrum the pores are extremely small. In- 

 terambulacra broad, consisting of large plates. Surface of all 

 the plates covered with fine granules, among which are numer- 

 ous, small, perforated, irregularly scattered tubercles. Apical 

 disk slightly in front of the center, narrow and elongate, the 

 four perforated genital plates arranged in pairs; the five ocular 

 plates are arranged in two pairs and one single plate, one of the 

 pairs between the two pairs of genital plates, the other situated 

 posteriorly and the single plate anteriorly placed. The oral 

 opening is transversely subelliptical, situated near the anterior 

 margin of the ventral surface. Anal opening subovate, situated 

 upon the truncated surface at the posterior margin of the test. 



The dimensions of a complete individual are : length, 50 mm. ; 

 width, 50 mm.; height, 28.12 mm. 



Formation and locality. Vincentown limesand, Vincentown 

 (154), Timber Creek (Clark). 



Geographic distribution. New Jersey. 



