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



The ambulacral areas are narrow, the posterior pair only slightly 

 longer than the anterior. 



The interanibulacral areas are wide and composed of large plates. 



The apical disk is small and situated nearly in the center of the upper 

 surface. • 



The mouth opening is small and placed forward of the center of the 

 base. The anal opening is situated in a nearly vertical sulcus that 

 is overhung at its upper extremity by a projecting arch (PI. xxvii, 

 Fig. 3c). 



Related forms. — Gatopygus pusillus is separated from G. oviformis by 

 its broader and slightly subquadrate form, less rounded sides, and 

 nearly central iiosition of the apical disk. 



Locality and, geological horizon. — Gatopyg us pusillus is from the lower 

 marl bed (upper Cretaceous) of Wordills, Monmouth county, New Jer- 

 sey. 



Collection. — TJ. S. National Museum. 



CASSIDULUS Lamarck. 



Cassidulus florealis (Morton). 



Plate XXVIII, Fig. 1 Or-l. 



"Clypeasier sp. Morton, 1830. Philadelpliia Acad. Nat. Sci. Jour., 1st ser., vol. 6, p. 202. 

 ^Clypeaster florealis Mortou, 1833. Amer. Jour. Sci., 1st ser., vol. 23, p. 294. 

 "Clypeaster florealis Morton, 1834. Syuop. Organ. Eenjains Cretaceous, p. 76, PI. 3, Fig. 



12, and PL 10, Fig. 12. 

 -P»/^(trM8/orm?is Agassiz and Desor, 1847. Cat rats., p. 141. 

 ^hjpeaster florealis Bronn, 1848. Index Pal., p. 312. 



Faujasia florealis d'Orbigny, 1853-'60. Pal6ont. frangaise, vol. 6, p. 319, PI. 920, 

 Figs. 5, 6. 



Faujasia florealis Desor, 1858. Synop. des Echinides fossiles, p. 318. 

 ^ Clypeaster florealis Gabb, 1859. Synop. Invert. Fossils, Cretaceous, p. 18. 



Cassidulus florealis Meek, 1864. Smith Misc. Coll., vol. 7 (177), p. 2. 

 "^Pygurus florealis Conrad, 1868. Geol. of New Jersey, Apji., p. 722. 



Cassidulus florealis Clark, 1891. Johns Hopkins University Circulars, No. 87, p. 76. 



Determinative characters. — Test subcouQidal in outline, subpentag- 

 onal, sliglitly longer in tlie anteroposterior diameter than the lateral, 

 rounded anteriorly, angular posteriorly; apex sliglitly forward of the 

 center. Ambulacra narrow ; poriferous zones j)etaloidal on the upper 

 two-thirds of the dorsal surface. Interambulacra wide, covered with 

 small perforated tubercles. Apical disk small, situated anteriorly. 

 Mouth opening pentagonal, with well-developed floscelle. Anal opening 

 supramarginal, in short, narrow sulcus. 



Dimensions. — Length, 1| inches; breadth, 1| inches; height, finch. 



Description. — This sj)ecies, the earliest of this genus recognized from 

 American deposits, has a subconoidal test of moderate height, with a 

 subpentagonal margin. The angularity is more pronounced posteri- 

 orly than anteriorly, the anterior portion of the margin being dis- 

 tinctly rounded. The antero-j)osterior diameter is but slightly greater 



