AHN'OLU^TIIE rALKONTOUKl Y AND STRATIGHAPHY OF SAN PEDKO. 177 



by .siiuiller pnllial sinus, lack of rid^e between cartilage-pit and anterior linamental 

 i:;roove, and by tlie interior radiating ridges and narrower anterior end. S[)eciniens 

 idenlilied l)y Dr. Dall. 



Found in llie lower San Pedro series at San Pedro and Deadman Island; an<l 

 in tlie upper San Pedro series at San Pedro, Deadman Island, Crawfish George's 

 and Los Cerritos. Also found in Pleistocene at Spanish Biglit, San Diego. The 

 specimen figured is from the upper San Pedro series at San Pedro, and is now in the 

 collection of Delos Arnold. 



Livincj. — Kodiak, Alaska, to San Diego (Cooper). 



Pleistocene. — San IVulro (Arnold) : San Diego (Cooper; Arnold). 



Pliocene. — Eagle Piairie, Humboldt County; Kirker's Pa.ss, Contra Costa 

 County (Cooper). 



Mocene.— Martinez; Half Moon Bay, San Mateo County; Sunol, Alameda 

 County; Siebeck's, Santa Clara County; Griswold's, San Benito County; Foxin's, 

 Santa Barbara County; Santiago, Los Angeles County (Cooper). 



Sulifauiily I'TEROPSIDIN.E. 



Genus Labiosa {Sclnai<ll) Mdller. 



Sliell large, tliin, intlated, broad and gaping behind, beaks adjacent; surface concentrically 

 striate; dorsal areas well defined; pallial sinus short, rounded, wide; ligament marginal, set off by a 

 prominent lamina of shell from the pit; a single obsolete and very short lateral in each valve before 

 and lieliind the pit; hinge-plate flattish behind, depressed and excavated in front. 



Type, Mttctrn anntiiui Spengler. 



Subgenus Raeta Gniij. 



vShell acutely rostrate behind; dorsal areas obscure, the surface of the valves more or less 

 vcrmiculate; pallial sinus deep, narrow, pointed; ligament submerged, e.xcept at the anterior end, 

 set off by a shelly ridge which roofs the apex of the pit, and partially supports the posterior arm of 

 the cardinal tooth; left cardinal small; right cardinal with anus coalescent above; a single anterior 

 and posterior lateral in each valve. 



Ty|.>e, hiitvdvlii cd iKiUcnl.iitd Say. 



129. Labiosa (Rseta) undulata Gunbl. 



Lutraria undu/ata Gld., Proc. Bost. Soc. Nat. Hist., Vol. IV, 1S51, p. 89; Bost. Jour. Nat. Hist., 



Vol. VI, 1S53, p. 391, PI. XV, fig. 7. 

 Rata undnlala Gld., C.\RPENTEr, Brit. Assn. Rept., 1863, p. 640. 

 Lutraria transmontana CoN. {fide Cooper, 7th Ann. Rept. Cal. St. Mm., iSSS, p. 247) [in part]. 



Shell of medium size, ovate, ventricose, thin; beaks a little anterior to center; anterior 

 broadly rounded and tumid; posterior narrowed, compressed and acutely rounded, the dorsal margm 

 being a rectilinear slope, gaping; surface concentrically undulated; cardinal tooth strong; posterior 

 lateral tooth small. 



( 23) 



Marcli K. 1903. 



