80 MAZATLAN BIVALVES 
ventrally.—384, 6 do. rather beaked.—385, 4 do. more trans- 
verse.—386, 7 do. transverse form, beak not indented.—887, 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. tumid.—392, 3 sp. yellowish 
var. normal.—393, 3 do. transverse.—394, 2 do. rounded.—395, 
1 do. tumid.—396, 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.—403, 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. shewing the inside.—In all 130 specimens. 
113. ANOMALOCARDIA SUBIMBRICATA, Sow. 
Venus subimbricata, Proc. Zool. Soc. 1835, p. 21.— Wood Suppl. 
App. pl. 15, f. 57.—Sow. Thes. Conch. p. 711, pl. 154, f. 35-38. 
Anomalocardia subimbricata, Desh. B. M. Cat. Ven. p. 117, no. 4. 
Only a very few small pairs and some young dead valves 
were found of this species, which further south is not uncom- 
mon. These few however exhibited remarkable differences. 
Sometimes the form was regular, sometimes extremely gibbous. 
Sometimes the concentric folds were rounded; sometimes 
as though the shell was raised at intervals and a fresh shell 
begun below; sometimes the radiating ribs were crossed by 
angular lamine, as in Ch. amathusia and gnidia. © In this 
state it may possibly be the V. cancellata of Menke’s Maz- 
atlan catalogue (Zeit. f. Mal. 1847, 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 the concentric ridges scarcely appear in 
the young shell, in which state it might easily be taken for 
another species. In one very young specimen, on the other 
hand, the concentric folds are sharp, while the radiating ribs 
are nearly evanescent. The largest specimen only measures 
long. 1°04, lat.1°1, alt. °77. 
Hab.—Puerto Portrero, in fine sand, 13 fm. Cwming.—Acapul- 
co, Sowerby.—S. W. Mexico, not uncommon, P. P. C.— 
Mazatlan ; extremely rare; L’pool Col. 
Tablet 409 contains 2 minute valves.—410, 5 valves of various 
forms.—411, the gibbous specimen. 
