f CLAKK.] CASSIDULUS FLOREALIS. 67 



tlian the lateral, while the height is a little iiioie tliaii one hall ol' t lio 

 same. The apex is a short distaiiee in front of the center of the iipju'r 

 surface, the slope of the anterior face being sharper than the i)Osterior 

 (PI. XXVIII, Fig. Ic). 



The ambulaeral areas are narrow. The ]>oriferous zones consist of a 

 double row of i)ores that are arranged in petaloidal form on the 

 upper two-thirds of the dorsal surface, and as phylloidal expansions in 

 the vicinity of the mouth edges (n. xxviii, Fig. le). In the ])etaloidal 

 portion the pores of the inner row are oval, those of the outer elon- 

 gated, and each pair united by a shallow furrow (PI. xxviii, Fig. 1/). 

 Toward the margin the pores are smaller and placed near together 

 (PL XXVIII, Fig. !(/), and so continue until near the peristome, when 

 the poriferous zones suddenly expand. At this point the jxa-es increase 

 in size and distance from one another. Between the oral lobes the ])o- 

 riferous zones again suddenly contract. 



The interambulacral areas are of unequal ^idth ; the anterior pair are 

 the narrowest; the three posterior are of about equal width and nearly 

 one-half wider than the anterior. The surface of the plates is irregu- 

 larly covered with numerous small perforated tubercles with sunken 

 areolas, betM een which are numerous microscopic granules (PI. xxviii, 

 Fig, li). 



The apical disk is comi)Osed of four perforated genital and five small 

 ocular plates. The fifth genital is apparently obsolete, as it could not 

 be observed on any of the several very perfect specimens examined. 

 The large right antero-lateral genital plate, the madreporite, extends 

 across the disk, forming a large portion of the center of that body (PI. 

 XXVIII, Fig. IJ). 



The mouth opening is large, pentagonal, and slightly nearer the 

 anterior margin. It is surrounded by five prominent lobes, that pro- 

 ject over the oral opening. Between the lobes the ambulacra are con- 

 tracted and beyond the same expand to form wide phylloidal areas. 

 The peculiar, somewhat star-shaped, form thus produced has been 

 termed floscelle by Desor (PI. xxviii. Fig. 16). 



The anal opening is small, Circular, and supra-marginal, and is situated 

 in a short, narrow sulcus (PI. xxviii, Figs. la-Id). 



Related forms. — Cassidulus Jforealis is allied to G. ajquorens, though 

 the latter is more depressed and more elongated. G. suhconicus pre- 

 sents some points of similarity, but has a more sharply defined pen- 

 tagonal outline, a differently situated anal opening, and more elongated 

 })ores in the outer rows of the x)etaloidal areas. 



Locality and geological horizon. — This species is reported from the 

 lower marl bed (ui)per Cretaceous) of ^ew Jersey and Delaware. 



Golkction. — Philadeli^hia Academy of Natural Sciences. 



