l68 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



Tiiherciilation. — Adorally tubercles only slightly larger than adap- 

 ically. 



Occurrence. — Upper Cretaceous (Cenomanian), Buda limestone, 

 Shoal Creek, Austin, Tex. 



Location of type specimen. — U. S. National Museum, 1 03701. 



Remarks. — Clark's {in Clark and Twitchell, 191 5, pi. 27, fig. 2a) 

 original figure of the type specimen of this species showed a small 

 round periproct. Lambert erected Porobrissits for this species, dis- 

 tinguishing it from Nucleopygus by the shape of its periproct. Cooke 

 (1946, p. 222) later removed the matrix from the sulcus, revealing 

 a longitudinally elongated periproct similar to that found in Nucleo- 

 pygus. Cooke (1955, p. 97) removed the species from Nucleopygus 

 because "Nucleopygus minor Agassiz, the type species of Nucleo- 

 pygus, appears to have a large, flush periproct." Cooke probably 

 studied Desor's figures oi N. minor (copied in Mortensen, 1948, 

 fig. 164). Desor's figure does show a flush periproct, but this figure 

 is not correct, as the periproct is definitely not flush, but in a groove 

 (see pi. 24, fig. 10). I agree with Mortensen in considering E. 

 angustatus congeneric with A^. minor. Both species are small, low, 

 with tetrabasal apical system, short, slightly developed petals, supra- 

 marginal, grooved periproct, and single-pored phyllodes. 



Genus HYPSOPYGASTER Bajarunas 



Hypsopygastcr Bajarunas, 1915. Ilypsopygaster, a new genus of sea-urchins 

 from the Danian deposits of Mangyshlak. Geo!. Vestnik-Petrograd, vol. i, 

 p. 230 (not seen). Type species by monotypy, Hypsopygastcr ungosensis 

 Bajarunas. 



GENERIC DESCRIPTION 



Small, posterior margin truncated with periproct high on trunca- 

 tion, apical system monobasal, three genital pores, no pore in left 

 anterior genital plate, petals slightly developed, ambulacra single 

 pored beyond petals ; bourrelets strongly developed, toothlike ; phyl- 

 lodes single pored, broad with few pores, buccal pores present ; 

 adorally tubercles much larger than adapically, naked sternal zone. 



Comparison with other genera. — Hypsopygastcr ungosensis re- 

 sembles Rhynchopygus inarmini Desmoulins from the Maestrichtian 

 in its small size, slightly developed petals, marginal outline of test, 

 broad phyllodes, pointed bourrelets, and naked pitted zone along inter- 

 ambulacrum 5. H. ungosensis differs in having a monobasal apical 

 system with three instead of four genital pores, a longitudinal peri- 



