124 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, I44 



PETALOBRISSUS LEFEBVREI (Fourtau) 



Plate 16, figures 4-6; text figure 104 

 Echinobrissus lefebvrei Fourtau, 19 14. Op. cit., p. 52, pi. 4, fig. 12. 



Material. — One specimen, the holotype, was studied. Although part 

 of the specimen is fractured, with portions of the test absent, all the 

 important characters are preserved. 



Shape. — Medium size, holotype 34.2 mm. long; test elongate with 

 smoothly rounded anterior margin, posterior margin with slight 

 truncation at anal groove, sides expanding posteriorly, with greatest 

 width posterior to center; adapical surface inflated, with greatest 

 height posterior to center ; adoral surface depressed around peristome. 



Apical system. — Anterior, tetrabasal, madreporite very large, oc- 

 cupying large central area, extending posteriorly, widely separating 

 posterior ocular plates, other genital plates small. 



Ambulacra. — Petals broad, equal, medium length, with slight tend- 

 ency to close distally. Interporiferous zones slightly wider than 

 poriferous, tapering slightly distally. Poriferous zones wide, tapering 

 distally, outer pore very elongated, almost slitlike, situated obliquely 

 distal to slightly elongated inner pore; conjugate. Single pores in 

 plates beyond petals. 



Periproct. — Supramarginal, between midway and two-thirds dis- 

 tance from apical system to posterior margin, oval longitudinally, in 

 deep, narrow groove, broadening slightly posteriorly, extending to 

 margin. 



Peristome. — Anterior, depressed, pentagonal, wider than high. 



Floscelle. — Bourrelets well developed, swollen, vertically sided. 

 Phyllodes slightly widened, single pored (text fig. 104), with pores 

 arranged in two series in each half-ambulacrum, approximately eight 

 in each outer series, four in each inner except in ambulacrum III, 

 where two or three ; buccal pores present. 



Tuberculation. — Tubercles larger adorally, slight naked sternal zone 

 in interambulacrum 5. 



Occurrence. — Upper Cretaceous (Turonian), Aubu Roash, West 

 Cairo, Egypt. 



Location of type specimen. — Holotype (25408, F 363) in Geo- 

 logical Museum, Cairo, Egypt. 



