MAZATLAN BIVALVES 23 
Hab.—Panama and St. Blas, 33 fm. R. B. Hinds, Mus. Cum- 
ing.—Mazatlan: one small pair nestling in Spondylus, and 
1 valve in Chama, L’pool Col. 
There is no doubt that the Mazatlan shell is the same as 
Mr. Cuming’s beautiful specimen, hitherto undescribed. Tablet 
77 contains the perfect specimen ; I reserve the valve. 
33. CORBULA PovuLATA, Sow. 
Proc. Zool. Soc. 1833, p. 35, 36.—Mill. Syn. Test. Viv. p. 230.— 
Rve. Conch. Ic. pl. 1. £.7.—Hanl. in Suppl. Wood’s Ind. Test. 
pl. 10, f. 52.—Hanl. Deser. Cat. p. 47.—B. M. Cat. D’ Ori. 
_ Moll. p. 70, no. 622. 
Tablet 78 contains 1 flat dead valve of regular oval shape 
slightly produced anteriorly, and very finely striated concen- 
trically, which may belong to this species. 
Hab.—In sandy mud, 7—17 fm. Xipixapi, and Bays of Montijo 
and Caraccas, Cuming.*—EKcuador: Xipixapi, D’ Orbigny.— 
Taboga, very rare but large, C. B. Adams.—Mazatlan ; 
one valve, L’pool Col. 
34. CorBULA——— , sp. ind. 
Tablet 79 contains a fragment of what must be when perfect 
a most beautiful and remarkable species. It is extremely thin, 
white, translucent, with a very sharp diagonal posterior keel, 
and another close to the margin. Umbos very near the anterior 
end. Shell smooth near the umbos; afterwards with waved 
concentric ridges; posterior part with deep pits at a sharp 
angle with the ridges. The whole shell with radiating rows of 
dots (probably epidermal) as in C. pustulosa. Inside a stout, 
- somewhat conical tooth in each valve, with corresponding pit. 
Interior surface very finely rugose. Mr. Hanley found a much 
more perfect specimen, which was most unfortunately crushed 
in transmission by the post. 
Hab.—Mazatlan ; from Spondylus Lamarckii ; L’pool & Havre 
Coll. es 
* Mr. Reeve further states ‘‘A few odd valves of this species were found by 
Mr. Cuming on the sands at Real Llejos and Mazatlan.” In reference however 
to this last locality, Mr. Cuming states that his extreme point north, along the 
West American coast, was Conchagua, Bay of St. Carlos (or Fonseca) : about 13° 
N. L. In all cases therefore where he is cited as the original collector at places 
north of this, the authority must be regarded as ** Museum Cuming,” 
