120 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



Remarks. — The Faujasidae are distinguished by their strongly 

 developed bourrelets, usually broad phyllodes, and broad petals. 



Genus PETALOBRISSUS Lambert 



Petalobrissus Lambert, 1916b. Mem. Soc. Acad. Aube, vol. 80, p. 82. T\'pe 

 species, Echinobrissus setifensis Cotteau, by original designation. 



GENERIC DESCRIPTION 



Small to medium, elongate, somewhat inflated, adoral surface 

 flattened to slightly pulvinate ; apical system anterior, tetrabasal, four 

 genital pores ; petals broad, equal, poriferous zones of same petal of 

 equal length with conjugate pores ; periproct supramarginal to mar- 

 ginal, longitudinal ; peristome anterior, pentagonal, wider than high ; 

 bourrelets strongly developed, inflated, projecting; phyllodes broad, 

 single pored, with two series of pores in each hal f -ambulacrum ; 

 buccal pores present; narrow naked area in median region in inter- 

 ambulacrum 5 adorally. 



Comparison unth other genera. — Petalobrissus is similar to Phyl- 

 lohrissus in the shape of its test, general petal arrangement with equal, 

 broad petals, supramarginal, longitudinal periproct, and tetrabasal 

 apical system. It differs from Phyllohrissus in its much more de- 

 veloped bourrelets, single-pored phyllodes, and in having buccal pores. 

 Petalobrissus is probably a descendant of Phyllobrissus as shown by 

 its more advanced phyllodes. and presence of buccal pores. As would 

 be expected, it occurs later in the Cretaceous than Phyllobrissus. 



Petalobrissus appears to be an ancestor of Hardouinia. It is veri- 

 similar to some of the more primitive species of Hardouinia and has 

 very similar phyllodes. It differs in having an anterior peristome and 

 less prominent bourrelets. 



Remarks. — Lambert considered this genus as only a subgenus of 

 Clypeopygus. Although somewhat similar in general appearance, they 

 are generically distinct. Clypeopygus is a more primitive form, with 

 double-pored phyllodes and lacking buccal pores. It occurs earlier 

 in the Cretaceous, although Lambert and Thier}- (1921, pp. 34S-349) 

 list many species that occur in the Turonian and Senonian. I have 

 seen specimens of four of these species, and in every case they have 

 single-pored phyllodes with buccal pores and should be referred to 

 Petalobrissus and not Clypeopygus. One of these species, Petalo- 

 brissus trigonopygus (Cotteau) is so similar to the t}-pe species of 

 Petalobrissus that it could almost be considered conspecific with it. 

 I have included a photograph (pi. 15. fig. 10) and a drawing of a 

 phyllode (text fig. loi) of this species. Petalobrissus djelfensis 



