ARNOLD— THE PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDRO. 140 



Distingiiisliahle from others of tliis geiui.s occurring in tlicse deposits; by the 

 even, close, lattice-like sculpture. Specimens identified by Dr. Dall. 



Common in upper Han Pedro series at San Pedro, Los Cerritos, Crawfish 

 George's, and Dcadman Island; rare in the lower San Pedro series at Deadman 

 Island. Found also in the Pleistocene at Twenty-sixth Street, San Diego. 



Living. — Monterey to Lower California (Carpenter). 



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



(Arnold). 



86. Venus (Chione) succincta Valenciennes. 



ViM'v. XIV, Fk;. I. 



Venus succincta Vai,., Humh. <S: Bonpl., Obs. sur Zool., p. 219, PI. LXVIII, fig. i, 1833. 



Chione succincta Val. =C. californiensis Brod. =C nuttalli Con. {^fide CARi'iiNTKR, Brit. 



Assn. Rept., 1863, p. 641.) 

 C/iione succincta Val. = Venus californica Con. = V. nuttalli CoN. = V. laynellifera Con. 

 (Wilkes' E.xped. and Jour. Conch., 1S65; not V. lame II i/e ra Coti.,]ovn:. Pliil. Acad., 

 Vol. VII, wXrich = Tapes staminea var. ruderatd) ^V. brcvilineata Con. =Chione 

 brevilineata Con. =1^. securis Shum. lyjide Gabb, Pal. Cal, Vol. II, p. 94, 1869). 

 Cooper, 7th Ann. Rept Cal. St. Min., 1888, p. 234. Keep, West Coast Shells, p. 187, 

 fig-. 159, 1892. Williamson, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 188. 

 Shell of medium size, thick, subcordiform; surface ornamented by several about equidistant, 

 slightly reflexed, low, concentric frills and numerous rounded, radiating ridges, most prominent on 

 the middle of the shell, which increase by intercalation and become flattened and less prominent as 

 the periphery is approached; lunule prominent, ornamented by both incremental laminx- and 

 rounded, radiating ridges; hinge narrow; two prominent cardinal teeth in each valve; pallial sinus 

 very shallow; margin crenulated. 



Dimensions. — Long. 55 mm.; alt. 50 mm.; diam. 32 nnn.; hinule 13.5 mm. 



The specimen whose measurements are given was the largest of the s]iecimens 

 examined. Distinguishable by the equidistant concentric frills, low, rounded, 

 radiating lines, and radiating lines on the lunule. 



Rather common in u])per San Pedro series of San Pedro, Los Cerritos, 

 Crawfish George's and Deadman Island. Found also in the Pleistocene of Barlow's 

 ranch, Ventura, and Twenty-sixth Street, San Diego. The specimen figured is 

 from the upper San Pedro series at San Pedro, and is now in the collection of 

 Delos Arnold. 



Living. — Santa Barbara to San Diego; Mexico; South America (Coojier). 



Pleistocene. — Santa Barbara to San Diego (Cooper): San Pedro (Arnold). 



Pliocene. — Seven Mile Beach, San Mateo County; San Fernando (Cooper). 



Miocene. — Oregon; Martinez; San Pablo; Griswold's, San Henito Count}'; 

 Foxin's, Santa Barbara County; Santa Monica (Cooper). 



Superfamily TAPETIN.E. 



Genus Tapes Megerle. 



Shell oblong, umbones anterior; margins smooth; teeth three in each valve, more or less 

 bifid; pallial sinus deep, rounded. 



Tapes Htleraia Lin no is a characteristic species. 



