ARNOLD — THE PALEONTOLOGY AND STUATIGKAPHY OF SAN PEDUO. 297 



Ceri//tit/fa .uicra/a Gld., Cpr., Proc. Zool. Soc, 1856, p. 226. KEi:r, West Coast Shells, p. 71, 



fijj. 56, i8g2. 

 Cerilhidea califomica Hald., Gabb, Pal. Cal., Vol. II, p. 79, 1869. Cooper, 7th Ann. Rept. Cal. 



St. Min., 1888, p. 233. Dali„ Trans. Wagner Inst. Sci., Vol. Ill, Part 2, 1892, p. 277. 



Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 205. 



Shell tiirreted; a|)e.\ decollated; whorls nine or ten, slightly convex, ornamented with three 

 or four s|)iral ridyos and luimcrovis transverse ri<lg(s, the two sets varying in prominence; suture 

 impressed, distinct; aperture subquadrate; outer lijj effuse, thickened, broadly rounded below, and 

 slightly produced in a columellar beak; inner lip straight above this beak. 

 Dimensions. — Alt. 25 mm.; lat. 9.5 mm.; dcfl. 22 degrees. 



Tlii.s is the only representative of tliis genus, and is one of the commonest of 

 the gastropods in the upper San Pedro formation. 



Found in tlie Pliocene of Deadman Island, lower San Pedro series of Dead- 

 man Island and San Pedro, and upper San Pedro series of Crawfish George's, Los 

 Cerritos, San Pedro, and Dea'dinan Island. Found in the Pleistocene at Twenty- 

 sixth Street and Pacific Beach, San Diego. 



Living. — Baulinas Bay to San Diego; Mazatlan (Cooper). 



Pleistocene. — San Pedro to San Diego (Cooper): San Pedro; San Diego 

 (Arnold). 



Pliocene. — San Fernando, Los Angeles County (Cooper) : San Pedro (Arnold). 



Family LXX. C.ECID.E. 



Genus Caecum Fleming. 



Young shell spiral in one plane, afterwards an arcuated tube, truncated posteriorly by the 

 loss of the spiral portion, and closed there by a convex septum or plug. 



Ccecum cornuoides is a characteristic species. 



324. Cascum californicum Ddll. 



Plate VIII, Fig. 6. 



C(Ecuvi cooperi Cpk., Brit. Assn. Rept., 1863, p. 655; not of Smith {Jide Dall). 



Cceaim californiaan Dall, Proc. U. S. Nat. Mus., Vol. VIII, 1885, p. 541. Tryon, Man. Conch., 



Vol. VIII, p. 219, PI. LXVI, fig. 65, 1886. Keep, West Coast Shells, p. 73, 1892. 



Dall, Trans. Wagner Inst. Sci., Vol. Ill, Part 2, 1892, ]i. 299. 



Shell small, tubular, curved, white, very slightly tapering; plug bent toward convex side; 

 aperture circular, slightly contracted; surface ornamented by thirty to forty prominent, narrow, 

 rounded rings. 



Dimensions. — Long, (maximum) 3 mm.; lat. 0.9 mm. 



Shell may be distinguished from G. crebricinctum by its small size and much 

 more prominent, narrow, sharp rings. 



Quite common in the upper San Pedro series of San Pedro and Crawfish 

 George's, and in the lower Sau Pedro series of Deadman Island and Sau Pedro. 



( 38 ) April 27, 1903. 



