88 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, I44 



longitudinally ; peristome anterior, pentagonal ; bourrelets well devel- 

 oped, inflated; phyllodes broadened, double pored, with pore pairs 

 in two series in each half -ambulacrum: lo to 12 pore pairs in each 

 outer series, 4 to 6 in each inner ; single buccal pores. 



Comparison with other genera. — Hypopygurus is most similar to 

 Pygorhynchus, having large petals, an inframarginal periproct, and 

 similar phyllodes. It differs in having buccal pores and straighter 

 poriferous zones. Lambert and Thiery (1921, p. 357) considered 

 Hypopygurus as a subgenus of Astrolampas, but the petals in Hypo- 

 pygurus have straight poriferous zones, not lanceolate as in Astro- 

 lampas, the apical system is more eccentric anteriorly, and it has 

 buccal pores. 



Range and distribution. — Cretaceous (Cenomanian) of Tunisia; 

 only one species known. 



DESCRIPTION OF TYPE SPECIES 



HYPOPYGURUS GAUDRYI Gauthier 

 Plate 13, figures 7, 8 ; text figure 72 



Hypopygurus gaudryi Gauthier, 1889a. Ech. foss., Tunisie, pp. 38-39, pi. 2, 

 figs. 19-23. 



Material. — Three specimens were studied in the Lambert Collec- 

 tion at the Sorbonne, and two in the Museum National d'Histoire 

 Naturelle, Paris. The specimen figured by Gauthier in his plate 2, 

 figures 22, 23, is herein designated as the lectotype. 



Shape. — Medium to large (largest specimen 61 mm. long), low, 

 elongate with pointed posterior margin ; adoral surface depressed. 



Apical system. — Anterior, tetrabasal with large genital plates. 



Ambulacra. — Petals broad, long, extending almost to margin, petals 

 I and V longer than others, straight, or slightly curved in some speci- 

 mens, widely open; interporiferous zones wide, increasing in width 

 distally ; poriferous zones wide, tapering distally ; pores strongly con- 

 jugate, outer pore slitlike, inner round to slightly elongate trans- 

 versely. 



Periproct. — Inframarginal, oval, elongated longitudinally. 



Peristome. — Anterior, pentagonal, slightly higher than wide. 



Floscelle. — Bourrelets well developed, inflated ; phyllodes broad- 

 ened, double pored (text fig. 72) with pore pairs arranged in two 

 series in each hal f -ambulacrum : 10 to 12 in each outer series, 4 to 

 6 in each inner; single buccal pores present. 



Occurrence. — Cretaceous (Cenomanian), Djebel Cehela, Tunisia. 



