NO. 3 CASSIDULOID ECHINOIDS — KIER 167 



poriferous; pores slightly conjugate, both inner and outer pore of 

 pair round; ambulacral plates single pored beyond petals. 



Periproct. — Supramarginal, longitudinal, high on slight posterior 

 truncation. 



Peristome. — Central, depressed, subpentagonal, vertically walled. 



Floscelle. — Bourrelets vertical, slightly inflated ; phyllodes single 

 pored, no widening of area, slight crowding (text fig. 142). 



TuhcrcuJation. — Adorally, tubercles of approximately same size as 

 adapically ; slight naked, granular zone in interambulacrum on some 

 specimens, absent on others. 



Occurrence. — Upper Cretaceous (Maestrichtian) of Holland and 

 Belgium. 



Location of type specimen. — University of Bonn, Germany. 



Synonym of NUCLEOPYGUS 



Porohrissns Lambert, 1916. Rev. crit. palaeozool., vol. 20, p. 169. Type species 

 by monotypy, Ech'mobrissus angustatus Clark, 1915. 



DESCRIPTION OF TYPE SPECIES 



NUCLEOPYGUS ANGUSTATUS (Clark) 



Plate 24, figures 12, 13; text figure 141 



Echinobrissus angustatus Clark, in Clark and Twilchcll, 1915- U. S. Gcol. Surv. 

 Monogr. 54, p. 69, pi. 27, figs. 2a-c. 



Material. — Eighteen specimens studied in the collection of Univer- 

 sity of Texas, and holotype and paratype in U. S. National Museum. 



Shape. — Small, average 15 mm. long, oval, low, greatest width 

 posterior to center, greatest height anterior, adoral surface depressed 

 around peristome. 



Apical system. — Very eccentric anteriorly, tetrabasal, with genital 

 2 extending posteriorly separating posterior oculars. 



Ambulacra. — Petals slightly developed, short, petal III shorter 

 than others, closing slightly distally, interporiferous zones equal in 

 width to poriferous zones; outer pore very slightly elongated trans- 

 versely, inner pore round, conjugate. 



Periproct. — Supramarginal, midway between apical system and 

 posterior margin ; elongate longitudinally, in groove extending to 

 posterior margin. 



Peristome. — Anterior, oval transversely, depressed. 



Floscelle. — Bourrelets slightly developed, phyllodes slightly devel- 

 oped (text fig. 141), single pored, six pores in each outer series, 

 three to four in each inner series; buccal pores present. 



