290 CRETACEOUS PALEONTOLOGY. 



1 89 1. Trematopygus crucifer Clark, Johns Hopkins Univ. 



Circ, vol. 10, No. 87, p. 76. 

 1893. Trematopygus crucifer Clark, Johns Hopkins Univ. 



Circ, vol. 12, No. 103, p. 52. 

 1893. Trematopygus crucifer Clark, Bull. U. S. G. S., No. 97, 



p. 63, pi. 27, figs I a-i. 

 1905. Trematopygus crucifer Johns., Proc. Acad. Nat. Sci. 



Phil., 1905, p. 7. 



Description. — Test ovate, very slightly contracted anteriorly^ 

 the sides and the outer portion of the base inflated. Ambulacral 

 areas long, lanceolate, well-defined, unequal, the posterior pair 

 the longest and the anterior unpaired area the shortest; pores 

 unigeminal, the poriferous zones clearly marked on the dorsal 

 surface with the pore pairs nearly horozontal in position, but to- 

 wards the ambitus the pores become smaller, those of each pair 

 nearer together and the pairs obliquely situated at the lower, 

 outer corner of each plate, near the margin of the oral opening 

 they again become larger. Interambulacral areas wide, composed 

 of large plates, the surface covered with irregular rows of small' 

 tubercles that are perforated and mammalated, the miliary space 

 covered with numerous, minute, irregularly-crowded granules. 

 Apical disk small, situated anteriorly ; the four genital plates dis- 

 tinctly perforated, those of the anterior pair situated much nearer 

 together than the posterior ones. Oral opening large, oblique, 

 situated in front of the center of the ventral side. Anal open- 

 ing supramarginal, large, oval, pointed at the upper extremity, 

 situated in an anal sulcus that makes a marked indentation of the 

 posterior margin and is bordered by two well-defined ridges. 



The dimensions of a complete individual are: length, 25 mm.; 

 width, 21.9 mm. ; height, 14 mm. 



Remarks. — This species is the only known American repre- 

 sentative of the genus, and it is not closely allied to any of the 

 European forms. 



Formation and locality. — Vincentown limesand, Timber Creek 

 (Clark). 



Geographic distribution. — New Jersey. 



