ARNOLD — THE PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDRO. 169 



Distinguishable from Macoma by the prominent ligaraental projection, hinge, 

 and less angular aspect. Specimens identifieil by Dr. Dall. 



Rather rare in the upper San Pedro series at San Pedro and Los Cerritos. 

 Living. — Santa Barbara to San Diego (Carpenter). 

 Pleistocene. — San Pedro (Arnold). 



Genus Tagelus Gray. 



Beaks median or subposterior; teeth two in each valve, simple, pedunculate; valves without 

 constriction or clavicle, straight; pallial sinus deep, reaching to or beyond the beaks; posterior 

 adductor scar rounded; pallial sinus with the ventral part partially coalescent with the pallial line. 



Type, Solen gibbus Spengler. 



117. Tagelus calif ornianus Conrad. 



Solecurtus calif ornianus Q.o^ ., ]o\\x . Phil. Acad. Sci., VdI. VII, 1S37, p. 233, PI. XVIII, fig. 3. 



Carpenter, Brit. Assn. Rept., 1863, p. 638. Cooper, 7th Ann. Rept. Cal. St. 



Min., 1888, p. 265. Keep, West Coast Shells, p. 201, fig. 172, 1892. 

 Tagelus cali/ornianus Coti., Dall, Proc. U. S. Nat. Mus., Vol. XV, 1892, p. 184. Dall, Trans. 



Wagner Inst. Sci., Vol. Ill, Part 5, 1900, p. 984. 



Shell of medium size, oblong-oval, convex, thin; umbones about central; posterior dorsal 

 margin runs straight back from umbo parallel with base; anterior dorsal margin slightly depressed, 

 beginning a little below and in front of umbo, parallel with base; extremities evenly rounded; basal 

 margin slightly contracted in middle; ligamental area slightly projecting; cardinal teeth, two in each 

 valve, sharji and thin; pallial sinus long and wide, pointed. 



Dimensions. — Long. 80 mm.; alt. 22 mm.; diam. 13 mm. 



Specimens identified by Dr. Dall. 



Rare in the lower San Pedro series at Deadaiiin Island and San Pedro; com- 

 mon in the upper San Pedro series at Deadman Island, Los Cerritos, Crawfish 

 George's, San Pedro, and Long Beach. Also found in the Pleistocene at Twenty- 

 sixth Street, San Diego. 



Living. — Santa Barbara to San Diego (Cooper). 



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

 San Diego (Arnold). 



Pliocene. — San Diego (Dall). 



Family XXXllI. DONACIDiE. 



Genus Donax (Linne) Lamarck. 



vShell elongate, smooth, with no posterior carination; ventral margins with obsolete serra- 

 tion; cardinal teeth two in each valve, the larger often bifid; laterals both in the left valve, the 

 anterior hardly distinguishable from the margin, of which it is a sort of modification. 



Donax trunculus Linne is a characteristic species. 



. 22) .J.iulK-iry 10, 1903. 



