222 
pending upon the species in question and is 
so depressed that the anterior and posterior 
sides almost touch within. The outer edge 
may be spinose, denticulate, or smooth. The 
left umbone is always curved behind the 
right. The anterior surface of the shell bears 
curved radiating cords which interlock at 
their ventral margin. They may be smooth 
or denticulated. These cords may be crossed 
by lesser concentric cords or threads. The 
sculpture of the posterior surface is weaker 
than that of the anterior. Here, too, a heart- 
shaped escutcheon is present. 
KEY TO THE SPECIES OF Corculum 
Margin of the shell strongly dentate. 
Anterior side decidedly dished. monstrosum 
Anterior side not decidedly dished. 
Anterior and posterior sides about equally 
convex. 
Shell large (up to 66 mm. hlgh)....cardissa 
Shell small (less than 25 mm. high). 
. dionaeum 
Anterior side much more convex than 
posterior side . obesum 
Margin of the shell not dentate. 
Anterior side convex. humanum 
Anterior side concave. 
Posterior side smoothish. levigatum 
Posterior side radially ridged. aselae 
Corculum monstrosum (Gmelin) 
(Plate 2, Figure 3) 
1782. Cardium monstrosum Chemnitz, Conch. 
Cab., vol. 6, pi. 14, figs. 149-150 (non-bino¬ 
mial). 
1791. Cardium monstrosum Gmelin, Linn. Syst. 
Nat., ed. 13, vol. 1, pt. 6, p. 3253, no. 29. 
1798 . Corculum dolorosum Roding, Museum Bol- 
tenianum, p. 189. 
1798 . Corculum injlatum Roding, ibid., p. 189. 
1819. Cardium inversum Lamarck, Anim. s. Vert., 
vol. 6, p. 16, no. 46. 
Chemnitz, while giving a good description 
and figures of this species in 1782, was a 
non-binomialist and does not figure in no¬ 
menclature. Gmelin based his name upon 
Chemnitz’s statements and figures, and estab¬ 
lished the specific name C. monstrosum. 
PACIFIC SCIENCE, Vol. 1, October, 1947 
Roding, when he created the generic name 
Corculum, cited both Gmelin’s and Chem¬ 
nitz’s Cardium monstrosum as the basis for 
his Corculum dolorosum. This, therefore, is 
an absolute synonym of C. monstrosum 
Gmelin. Roding also lists Corculum injla- 
tum, a new name, which he bases upon 
Cardium monstrosum Gmelin and Favannes 
Conchyliologie, pi. 51, f. El. I am unable 
to recognize anything in our collection 
that corresponds completely with Favan- 
nes’ drawing, which I am inclined to believe 
places the escutcheon on the wrong side. To 
dispose of the name Corculum injlatum 
Roding, I am here designating his first cita¬ 
tion "Gmel. Cardium monstrosum” as type 
of Corculum inflatutn Roding, which adds 
this name to the list of synonyms of C. mon¬ 
strosum. 
To this list must also be added the Car¬ 
dium inversum Lamarck, which was like¬ 
wise based on Chemnitz’s figures 149-150. 
This species is differentiated from the rest 
by its extremely convex, comparatively 
smooth posterior side and denticulated outer 
margin. 
Shell soiled or yellowish white. The an¬ 
terior surface is convex along its ventral 
margin excepting at the outer edge, which is 
very strongly upturned, lending this surface 
a deeply dished aspect. It is marked by 
radiating cords which are separated by spaces 
a little wider than the cords. The cords are 
sharply spinose, the spines becoming weak¬ 
ened on the outer cords. The margin is 
strongly dentate. In addition, the surface is 
marked by fine threads paralleling the cords 
and stronger, very regularly disposed incre¬ 
mental lines. The posterior surface is very 
convex. It bears three poorly developed, 
widely separated, finely nodulose, radiating 
cords adjacent to the escutcheon. Outward 
from these, merely indicated radiating cords 
are present. Lines of growth and radiating 
finer threads are scarcely indicated. 
