182 CALIKOIJNIA AC'ADKMY OF SC'IENCl*. 



One lu-arlv perfect rijj;!!! valve rnun llic lower San Pedro seiies at Deadinan 

 Islaiul was t»l)taine(l liv Mrs. Oldroyd, is linnriMl in ilii< |ia|ier, ami is ikiw in the 

 collection of Mrs. Oldroyd. I^ater another valve was found at the same locality by 

 Delos Arnold. 



Licing. — Piiget Sound to Santa Barbara, 40 to 00 fathoms (Carpenter). 



/V('js<oce«e.- San Pedro (Oldroyd; Arnold). 



Family XXXViii. SAXICAVI D.E. 



Genus Panopea ^[en((rd. 



Slicll cciuivalve, thick, oblong, gaping at eacii end; ligament external, on ])roniiiient ridges; 

 one prominent tooth in each valve; pallia! sinus deep. 



Ml/a ghjcymeris Born, is a characteristic species. 



135. Panopea generosa Gould. 



Panopea generosa Gld. , Proc. Bost. Soc. Nat. Hist. \'ol. Ill, iSsp, p. 215. Wilkes' E.xped., 



p. 385, PI. XXXIV, fig. 507, 1852. 

 Glycimeris generosa Gld., H. & A. Adams, Gen. Rec. Moll., p. 350, 1853. Cpr., Brit. A.ssn. 



Rept., 1863, p. 637. Gabr, Pal. Cal., Vol. II, p. 89, 1S69. Cooper, 7th Ann. Rept. 



Cal. St. Min., 1888, p. 241. Keep, West Coast Shells, p. 209, fig. 178, 1892. 



Williamson, Proc. U. S. Nat. Miis., Vol. XV, 1892, p. 183. Dall, Wagner Inst. 



Sci., Vol. Ill, Part 4, 1898, p. 830. 



"Shell large, rather thin, nearly equilateral, the beaks slightly anterior, the dorsal and 

 ventral margins in the full grown shell parallel and nearly straight, the pedal margin evenly rounded, 

 the nymph narrow, and the attached edge of the ligament very short ; the pallial sinus wide 

 and shallow. 



" Dimensiotis. — Long. 182 mm.; alt. no mm.; diameter 60 mm." 



Dr. Dall gives the above description of a living, typical P. generosa Gould 

 from Paget Sound. In the same paper (Tertiary Fauna of Florida, Trans. AVagner 

 Inst. Sci., Vol. Ill, Part 4, p. 831) he describes two new varieties of this same species 

 which he thinks have constant differences enough to warrant the separation. Variety 

 mllda Dall has a heavy, somewhat arcuate, shell, strong nym]>h, a ligamentary 

 attachment twice as long as in the typical form, and a deep pallial sinus. This and 

 the typical form are found from Puget Sound to San Diego. Variety globosa Dall 

 hits a short, thin, inflated shell with the beaks nearer the anterior end, which is ex- 

 panded and rounded in the pedal region; opposite margins not parallel; pallial sinus 

 small and wide. Found at head of Gulf of California. 



Dall also classes together Mya abrupta Con. and Glycimeris estrellana Con., of 

 the Miocene of California and Oregon, and differentiates them from P. generosa Gld. 

 under the name P. estrellana Con. 



Two imperfect valves from the upper San Pedro series at Los Cerritos were 

 identified by Dr. Dall as typical P. generosa. 



Rare in the Pliocene and lower San Pedro series at Deadman Island; and in 



