314 [December, 



the extremity situated more nearly on a line with the beak than the base ; disk 

 concentrically rugoso-striate. Length IJ- inches. 

 Z/oca%. Monterey, Gal. Dr. Newberry. 



ARCA, Lin. 



1. Area canalis. Subtrapezoidal, ventricose ; ribs 2426, flattened, scarcely 

 prominent, divided by a longitudinal furrow; disk concentrically wrinkled ; umbo 

 ventricose ; summits prominent, remote from the centre. Length 2^ inches. 

 Height 1| inches. 



Locality. Santa Barbara, Gal. 



2. Area trilineata. Trapezoidal, somewhat produced, inequilateral, ventri- 

 cose ; ribs 2224, scarcely prominent, square, wider than the intervening spaces, 

 ornamented with three impressed or four raised lines ; disks concentrically wrin- 

 kled ; summits prominent; beaks approximate. Length 3 inches. 



Locality. Occurs with the preceding. 



3. Area conyesta. Rhomboidal, ventricose, inequilateral ; ribs about 27, con- 

 vex on the back, wider than the intervals which are transversely striate ; an- 

 terior ribs crenate ; ligament margin elevated ; posterior end obtusely rounded ; 

 summits prominent. Length f inch. 



Locality. California. Dr. Newberry. 



AXINiEA, Poll. PECTUNCULUS, Lam. 



Axincea barbarensis. Lentiform, subequilateral, concentrically wrinkled ; ribs 

 about 37, scarcely prominent, flat, defined by an impressed line, wanting on the 

 submargins and obsolete towards the base ; summits slightly prominent. 

 Length 1| inches ; height rather more than 1|- inches. 



ARCOPAGIA. 



Arcopagia medialis. Oval, both valves slightly ventricose anteriorly ; upper 

 valve ,much contracted or concave towards the umbonal slope which is angu- 

 ated ; post-umbonal slope slightly contracted in the middle, emarginate at base : 

 the corresponding slope of the lower valve deeply folded, reflected towards the 

 extremity; disks rugoso-striate concentrically. It has an affinity to A bijjUeaia, 

 Conrad, but is proportionally longer. 



ioca/%. Monterey Co., Cal. A. S. Taylor. 



TAPES, Sowerby. 



Tapes linieatum. Oblong-oval, ventricose ; buccal side short, extremity ob- 

 tusely rounded ; anal side elongated, end regularly rounded ; ligament margin 

 long, oblique, straight ; disks radiated with fine, unequal lines, except on the 

 post-umbonal slope which is entire. Length 2 inches. 



Locality. Dr. Newberry. 



CRYPTOMYA, Conrad. 



Cryptomya ovalis. Oval, compressed, posterior end truncated ; umbonal slope 

 angulated on th umbo ; beaks medial ; basal margin medially truncated ; disk 

 medially flattened. 



Locality. Monterey Co., Cal. Dr. Newberry. 



CYCLAS, Klein, LUCINA, Lam. 



Cyclas teirica. Suboval, compressed? very inequilateral, somewhat oblique ; 

 disks concentrically striate ; larger strije prominent, acute, distant, the intervals 

 with 4 or 5 unequ.al, fine, wrinkled lines; beaks scarcely prominent above the 

 dorsal line. Length 1| inches. 



Locality. lloni&vbj Co., Cal. A. S. Taylor. 



