NO. 3 CASSIDULOID ECHINOIDS — KIER 8l 



higher posteriorly ; margins evenly rounded, adorally slightly flattened 

 around peristome. 



Apical system. — Anterior, tetrabasal (text fig. 65), genital 2 large, 

 extending posteriorly, separating posterior genital plates ; other geni- 

 tal plates small. 



Ambulacra. — Petals broad, open, petal III shorter than others, all 

 extending over two-thirds distance from apical system to margin ; 

 interporiferous zones very wide, over twice width of poriferous 

 zones, expanding distally; poriferous zones narrow, tapering distally, 

 pores conjugate, outer elongate transversely, inner round ; pore pairs 

 in plates beyond petals. 



Adoral interamhulacra. — Plates regularly alternating, double series 

 continuing to peristome. 



Periproct. — Inframarginal, flush, longitudinal, at end of slight 

 posterior prolongation. 



Floscelle. — Bourrelets slightly developed; phyllodes double pored, 

 not widened, slightly depressed, two series of pore pairs in each 

 half-ambulacrum : five to six pore pairs in each outer series, four 

 or five in each inner ; in some specimens, alternate pore pairs in outer 

 series in plates not extending to midline (text fig. 64) ; most of inner 

 pore pairs in occluded plates. 



Tuberculation. — Tubercles on adoral surface approximately same 

 size as on adapical. 



Occurrence. — Lower Cretaceous (Barremian) of France and 

 Switzerland. 



Location of type specimen. — Not known. 



Genus PYGORHYNCHUS L. Agassiz 



Pygorhynchus L. Agassiz, 1839. £ch. foss. Suisse, pt. i, pp. 53, 99. Type 

 species by subsequent designation, Lambert (1898, p. 162), Catopygus obovatus 

 L. Agassiz. 



Synonym : Botriopygus d'Orbigny. 



GENERIC DESCRIPTION 



Medium to large, usually with greatest width posterior to center, 

 anterior margin blunt, posterior pointed, low, or in a few species 

 moderately inflated; apical system tetrabasal, anterior, four genital 

 pores ; petals well developed, broad, slight tendency to close distally, 

 narrow poriferous zones with conjugate pores, all ambulacral plates 

 double pored ; periproct marginal to inframarginal, longitudinal ; 

 peristome anterior, depressed, oblique or regular; bourrelets well 



