192 , PALEONTOLOGY OF THE SURVEY. 



TAPES? Niihlf. 



Tapes MONTANA, PI. 5, figs. 3and5.— Suboval, ventricose, very inequilateral ; posterior margin 

 very oblique and rounded, end obtusely rounded; basal margin sliglitly contracted medially ; 

 disk witb concentric impressed lines. 



Locality. — San Buenaventura. 



Tapes Inezensis, PI. 7, fig. 1. — Less ventricose tban the preceding, with a rounded base^ 

 and prominent concentric lines. 



Locality. — Santa Inez mountains. 



VENUS, Lin. . 



Venus Pajaroana, PI. 4, figs. 1 and 2. — Obliquely ovate-obtuse, ventricose, very inequilateral ; 

 anterior margin obtusely rounded, posterior side sub-cuniform ; posterior end truncated obliquely 

 inwards. 



Locality. — Pajaro river, Santa Cruz. 



ARCOPAGIA., Brown. 



Aecopagia unda, pi. 4, figs. 3 and 4. — Subtriangular ; right valve profoundly ventricose ante- 

 riorly ; profoundly sinuous posteriorly, or contracted from beak to beak ; anterior end regularly 

 and obtusely rounded ; beaks nearly central ; valves rugose-striate concentrically. 



Locality. — Shore of Santa Barbara county, California. 



This species is described from one imperfect valve, which resembles A. hiplicata, Con. It is 

 somewhat larger than that species, has a much larger umbo, is less curved, being almost 

 straight. In the same rock is a cast of a bivalve resembling a shell I have described under the 

 name of Carditamon carinata. There is in the collection another cast of this shell in lime- 

 stone, from Estrella. 



CTCLAS, Klein. LUCINA, Lam. 



Cyclas permacra, pi. 7, fig. 4. — Compressed, inequilateral ; concentrically rugose-striate, 

 strite distinct and acute. 



Locality. — Sierra Monica. 



The specimen described is imperfect. It somewhat resembles C. panduta, Con., {Lucinacom- 

 pressa, Lee,) but differs in having prominent lines. 



Cyclas estrellana, PI. 6, fig. 6. — Sulvoval, inequilaterally ventricose ; valves extremely 

 thick ; surface with concentric lines, probably mere lines of growth on the middle^ but promi- 

 nent and robust anteriorly. 



Locality. — Estrella. 



Length, 3^ inches. A broken cast, with a large portion of the shell of the left valve crys- 

 tallized, and exhibiting a remarkable thickness over the umbo. 



AECA, Lin. 



Arca obispoana, pi. 5, fig. 1. — Oblong, or trapezoidal ; very inequilateral, ventricose; ribs 

 about 26, little prominent, flattened ; sides rectangular with the ba(?k ; transversely rugose, 

 or sub-crenulated. 



Locality. — San Luis Obispo valley, California. 



This species has been described from very perfect casts in an argillaceous gray marl. 



