142 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



However, in Pygurus the phyllodes are double pored with no buccal 

 pores and the apical system is tetrabasal. 



Range and distribution. — Upper Cretaceous (Maestrichtian) , Texas. 



DESCRIPTION OF TYPE SPECIES 



DOMECHINUS CHELONIUM (Cooke) 

 Plate 18, figures 1-5 



Faiijasia chelonium Cooke, 1953. U. S. Geol. Surv. Prof. Pap. 254-A, p. 14, 

 pi. 4, figs. 11-14. 



Material. — Only one specimen, the holotype, is known of this 

 species. It is a well-preserved specimen showing the apical system 

 and phyllodes. 



Shape. — Medium size, holotype 30.5 mm. long, broad, width 

 slightly less than length, anterior margin gently rounded, sides 

 straight, posterior pointed ; adapically highly inflated with steep sides ; 

 adorally flat to slightly depressed. 



Apical system. — Slightly anterior, monobasal, with four genital 

 pores. 



Ambulacra. — Petals conspicuous, broad, equal, closed, interpo- 

 riferous zones extremely wide, tapering distally, poriferous zones 

 narrow with conjugate pores, outer pore slightly elongated trans- 

 versely, inner circular. 



Periproct. — Marginal to inframarginal, transverse, very small. 



Peristome. — Anterior, small, pentagonal, width equaling height. 



Floscelle. — Eourrelets strongly developed, pointed (pi. 18, fig. 5), 

 toothlike, jutting into peristome ; phyllodes broad, single pored, with 

 pores in two series in each half-ambulacrum : five to seven in each 

 outer series, two in each inner ; pores widely separated from peristome ; 

 buccal pores on edge of peristome. 



Ttiberculation. — Tubercles very small on both adapical and adoral 

 surfaces ; smaller on median tract of interambulacrum 5, adorally. 



Occurrence. — Upper Cretaceous (Maestrichtian), Escondido for- 

 mation, Texas. 



Location of type specimen. — U. S. National Museum. 



Genus FAURASTER Lambert 



Fauraster Lambert, in Lambert and Thiery, 1924. Ess. nom. rais., p. 396. Type 

 species by original designation, Fauraster prisms Lambert. 



