170 CALIFORNIA ACADEMY OF SCIENCES. 



ii8. Donax californica Conrad. 



Plate XIII, Fig. 9. 



Donax californica Con., Jour. Phil. Acad. Sci., Vol. VII, 1837, p. 254, PI. XIX, fig. 21; (not of 

 Carpenter, Brit. Assn. Rept., 1863, p. 640.); (not of Cooper, 7th Ann. Rept. Cal. 

 St. Min., 1888, p. 238); (not of Keep, West Coast Shells, p. 192, fig. 164, 1892); (not 

 of Williamson, Proc. U. S. Nat. M us., Vol. XV, 1892, p. 186). = /?. navicula 

 Hanley (fide Dall, Trans. Wagner Inst. Sci., Vol. Ill, Part 5, 1900, p. 968). 



Donax flexiiosus (not of Gould, Bost. Jour. Nat. Hist., Vol. VI, 1857, p. 394, PI. XV, fig. 8); 

 (not of Cpr., Brit. Assn. Rept., 1863, p. 640). ? Cooper, 7th Ann. Rept. Cal. St. Min., 

 1888, p. 238. Keep, West Coast Shells, p. 192, 1892. ? Williamson, Proc. U. vS. Nat. 

 Mus., Vol. XV, 1892, p. 186. 



Shell small, elongate-oval, rather pointed at both ends, thin; anterior end produced, quite 

 sharply rounded; posterior portion over one-half length of anterior, rounded end; surface obscurely 

 sculptured with fine radiating furrows; concentric, incremental sculpture sometimes visible; hinge 

 and teeth as in D. laevigata except more delicate; interior of margin finely crenulated. 



Dimensions. — Long. 18 mm.; anterior portion 11 mm.; posterior 7 mm.; alt. 8 mm.; 

 diam. 6 mm. 



Distinguishable from D. hmngata by smaller, narrower, thinner shell, more 

 elongated posterior portion and much less steeply sloping dorsal margin on this end. 

 This is the true D. californica Conrad, and not the californicas of Carpenter and 

 other later writers (see synonymy above). Specimens identified by Dr. Dall. 



Rare in the lower San Pedro series at Deadmaii Island and San Pedro; and 

 in the upper San Pedro series at San Pedro. The specimen figured is from the lower 

 San Pedro series at Deadman Island, and is now in the collection of Delos Arnold. 



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



Pleistocene. — San Pedro (Arnold). 



119. Donax laevigata De.shayes. 



Plate XIII, Fig. 8. 



Donax IcBvigata Deshayes, Proc. Zool. Soc, 1854, p. 352. Reeve, Conch. Icon., Vol. VIII, 

 PI. V, fig. 31. Dall, Trans. Wagner Inst. Sci., Vol. Ill, Part 5, 1900, p. 969. 



Donax cali/ornicus (not. of Conrad, Jour. Phil. Acad. Sci., Vol. VII, 1837, p. 254, PI. XIX, fig. 21). 

 Carpenter, Brit. Assn. Rept., 1863, p. 640. Cooper, 7th Ann. Rept. Cal. St. Min., 

 1888, p. 238. Keep, West Coast Shells, 192, fig. 164, 1892. Williamson, Proc. 

 U. S. Nat. Mas., Vol. XV, 1892, p. 186. 



Donax obesus, Gld., Proc. Bost. Soc. Nat. Hist., Vol. IV, 1851, p. 90; Bost. Jour. Nat. Hist., 

 Vol. VI, p. 394, PI. XV, fig. 9, 1857. 



Shell rather small, trigonal, convex, wedge-like, closed; anterior portion produced, rounded, 

 upper margin straight; posterior portion very short and dorsal margin nearly straight, also angulated 

 at base; surface obscurely sculptured by fine radiating lines; incremental sculpture generally visible; 

 interior of margin strongly crenulated; hinge teeth two in each valve; laterals one anterior and one 

 posterior in each valve; pallial sinus deep. 



Dimensions. — Long. 20.5 mm.; anterior portion 14 mm.; posterior 6.5 mm.; alt. 12 nnn.; 

 diam. 8 mm. 



