CBETACEOUS ECHINODEBMATA. 73 



The apical system is small, excentric, and situated far anterior to the apex. 



The peristome is small and situated nearer the anterior margin. 



The periproct is oval and placed at the upper part of a nearly vertical anal sulcus. The 

 upper margin of this sulcus forms a beak-shaped prominence, that overhangs the opening. 



Belated forms. — C oviformis is separated from 0. pusillus Clark, by its narrower outline, 

 more inflated sides, and the - anterior position of its apical system. In form it is somewhat like 

 C. columbarius of Europe, but is distinguished from it by the position of the apical system. 



Locality. — -Timber Creek, N. J. 



Geologic horizon. — Vincentown sand of Rancocas group, Upper Cretaceous. 

 ■ Collection. — Academy of Natural Sciences of Philadelphia (1477). 



Catopygus pusillus Clark. 

 Plate XXIX, figures 3a-d. 



Catopygus pusillus Clark, 1S91, Johns Hopkins Univ. Circ, vol. 10, No. 87, p. 76. 

 Catopygus pusillus Clark, 1893, Johns Hopkins Univ. Circ, vol. 12, No. 103, p. 52. 

 Catopygus pusillus Clark, 1893, U. S. Geol. Survey Bull. 97, pp. 65, 66, PL XXVII, figs. 3a-d. 



Catopygus pusillus Weller, 1907, Cretaceous paleontology of New Jersey: Geol. Survey New Jersey, p. 292, PI. XI, 

 figs. 16-19. 



Determinative characters. — Test ovate to subquadrate, rounded anteriorly, subquadrate 

 posteriorly, broader behind than before; upper surface elevated; base concave. Ambulacra 

 narrowly lanceolate, subpetaloidal on the upper surface. Apical system small, nearly central. 

 Peristome small, anteriorly placed. Periproct oval in vertical sulcus beneath overhanging arch. 



Dimensions. — Characteristic form: Length 15.6 millimeters; width 14 millimeters; height 

 9.4 millimeters. 



Description. — All the specimens of this species examined by the writer are casts, which are, 

 however, sufficiently well preserved to allow determination of all the more important characters. 

 The test is ovate to subquadrate, occasioned by the slight angularity of the posterior margin. 

 The anterior portion is regularly rounded. 



The ambulacra are narrow, the posterior pah only slightly longer than the anterior. 



The interambulacra are wide and composed of large plates. 



The apical system is small and situated nearly in the center of the upper surface. 



The peristome is small and placed forward of the center of the base. The periproct is situ- 

 ated in a nearly vertical sulcus that is overhung at its upper extremity by a projecting arch. 



Related forms. — Catopygus pusillus is separated from C. oviformis by its broader and slightly 

 subquadrate forni, its less rounded sides, and nearly central position of its apical system. 



Locality. — Wordills, Monmouth County, N. J. 



Geologic horizon. — Merchantville clay of Matawan group, Upper Cretaceous. 



Collection. — U. S. National Museum (2210). 



Catoptgus williamsi Clark. 

 Plate XXIX, figures 4a-d. 



Catopygus williamsi Clark, 1907; in Weller, Cretaceous paleontology of New Jersey: Geol. Survey New Jersey, pp. 

 292-293, PL XII, figs. 1-4. 



Determinative characters. — Test ovate, slightly broader posteriorly; upper surface rounded 

 and somewhat elevated; lower surface concave. Apex posterior to apical system. Ambulacra 

 subpetaloidal. Peristome small, near anterior margin. Periproct small, low clown on slightly 

 truncated posterior margin. 



Dimensions. — Length 26 mdlimeters; width 22 millimeters; height 15 millimeters. 



Description. — The single specimen of this species is a well-preserved cast that clearly shows 

 all of the more important diagnostic features. The test is ovate, slightly broader posteriorly. 

 The posterior margin is but little truncated, affording a nearly oval outline to the ambitus. 

 The upper surface is somewhat elevated, but it is not a highly inflated form. The lower surface 

 is clearly concave. 



