80 MAZATLAN BIVALVES 



ventrally. — 384, 6 do. ratlier beaked. — 385, 4 do. more trans- 

 verse.— 386, 7 do. transverse form, beak not indented. — 387, 6 

 do. very transverse and indented. — Groups shewing colour. 

 Tablet 388 contains 2 sp. whitish var. normal. — 389, 2 do. trans- 

 verse. — 390, 2 do. flat. — 391, 2 do. tomid. — 392, 3 sp. yellowish 

 var. normal. — 393, 3 do. transverse. — 394, 2 do. rounded. — 395, 

 1 do. tumid. — 390, 3 do. orange var. — 397, 3 sp. dark var. nor- 

 mal.— 398, 3 do. elongated.— 399, 3 do. rounded.— 400, 3 do. 

 tumid. — 401, 3 do. form of A. subimbricata. — 402, 3 sp. broad 

 bands. — 4D3, 3 do. speckled.— 404, 3 do. narrow bands. — 405, 2 

 do. and a valve, bands very faint. 



Tablet 406 contains 3 sp. strongly rugose. — 407, 3 do. smooth 

 form. — 408, 3 do. skewing tbe inside. — In all 130 specimens. 



113. AlfOMALOCAEDIA SUBIJIBEICATA, SotO. 



Venus subimbricata, Proc. Zool. Soc. 1835, p. 21. — Wood Siippl. 



App. pi. 15, f. o7.— Sow. Thes. Conch, p. 711, pi. 154, f. 35-38. 



Anomalocardia subimbricata, Desh. B. JT. Cat. Ten. p. 117, no. 4. 



Only a very few small pairs and some young dead valves 

 were found of this species, wkieb furtber south is not uncom- 

 mon. These few however exhibited remarkable differences. 

 Sometimes the form was regular, sometimes extremely gibbous. 

 Sometimes the concentric folds were roujided ; sometimes 

 as though the shell was raised at intervals and a fresh shell 

 begun below ; sometimes the radiating ribs were crossed by 

 angidar lamincne, as in Ch. amathusia and gnidia. In this 

 state it may possil^ly be the V. cancellata of Menke's Maz- 

 atlan catalogue fZeit. f. Mai. 1817, p. 191) ; unless indeed 

 that be a young specimen of one of the species above named, 

 from which it may be told by the extremely minute pallial 

 sinus. Very rarely tlie concentric ridges scarcely appear in 

 the yoiuig shell, in which state it might easdy be taken for 

 another species. In one verj^ young specimen, on the other 

 hand, the concentric folds are shai^j, whUe the radiating ribs 

 are nearly evanescent. The largest specimen only measures 

 long. I- 01, lat.Vl, alt. '77. 



JTa^). — Puerto Portrero, in fine sand, 13 fm. Cuming. — Acapul- 

 co, Sowerby. — S. W. ]\Iexico, not imcommon, P. P. C— 

 Mazatlan ; extremely rare ; L'pool Col. 



Tablet 400 contains 2 minute valves. — 410, 5 valves of various 

 forms. — 411, the gibbous specimen. 



