MAZATLAN BIVALVES 95 
satis; parte anteriore punctis ovalibus wmpressis decussaté ; 
dentibus lateralibus approximatis. 
‘This charming little creature has a general resemblance told a 
minute C. costatum; but the large ventral coste are rather 
rounded, with a little one on each side making them appear 
somewhat trigonal. The anterior portion is strongly indented 
with oval pits. The appearances it presents under the micros- 
cope vary greatly according to the direction of the light. The 
young shells have fewer ribs near the hinge, where the teeth 
are not fully developed; are rather less equilateral; and are 
granulose on the ribs. Long. ‘12, lat. *11, alt. °08. 
Hab.—Mazatlan; in Chama and Spondylus washings; ex- 
tremely rare. 
Tablet 461 contains 2 valves, the largest and the smallest. 
134. CARDIUM GRANIFERUM, Brod. 5 Sow. 
Zool. Journ. vol. iv. p. 367.—Sow. Conch. Ill. no. 38, pl. 49, 
f. 17.—Rve. Conch. Syst. pl. 76, f. 17 :—Conch. Ic. pl. 8, 43.— 
Hanl. Descr. Cat. p.137.—C. B. Ad. Pan. Shells, p. 266, 
no. 430.—B. WM. Cat. D’ Orb. Moll. p. 73, no. 652. 
The smallest valve found, which only measures ‘03 across, 
scarcely shews a trace of teeth. The young shells are nearly 
rectangular at the posterior end ; when older, they are obtuse 
angled. The interstices between the ribs are decussated by a 
series of rectangular impressed pits laid transversely. The 
largest specimen found measures only long. ‘12, lat. *12, alt. °06. 
Hab.—Dug from a depth of about 6 inches in the mud of the 
Estaro de Mazatlan; Lieut. Belcher.—Gulf of Nicoyia and 
Xipixapi; Cuming, D’ Orbigny.—Panama, extremely rare, 
C. B. Adams.—Mazatlan ; a very few young valves and frag- 
ments in the washings of Chame and Spondyli; Z’pool Col. 
Tablet 462 contains the largest (imperfect) valve, and two 
small ones. 
135. PCarpIum ————, sp. ind. (g.) 
2C. t. guniore suborbiculari, albidd, valde inequilaterali ; 
margine dorsali postice recto, antice concavo ; costis circiter xviii. 
validis, rotundatis, approximatis, tuberculis latis armatis ; 
dentibus elongatis, lateralibus distantibus. 
