420 
MOLLUSCA. CARDIADiE. Ispcardia. 
laud, and those of the Mediterranean examined by Poli. “ The foot of the 
Mediterranean species is much less pointed, shorter, less rugose, and of a 
somewhat ditferent and lighter colour than the same part in our animaL 
The margin of the mantle in Poli’s figure is strongly serrated, and of the 
same ferruginous hue as the rest of the animal ; in ours it is plain, and in, 
the healthy animal of a bright orange, while its body is of a yellowish white.”’ 
Zool. Journ. No. 7-361. 
EXTINCT SPECIES. 
1. I. minima — Globose, subdeltoid ; anteriorly slightly truncated, poste- 
riorly flattened ; cordate. — Sower. Min. Conch, t. ccxcv. f. 1. — Lower Oolite. 
2. I. tener—OhovaXe^ with produced beaks ; anteriorly subtruncated, pos- 
teriorly rounded; shell very thin, smooth Soiver. Min. Conch, t. ccxcv. f. 2. 
— Lower Oolite. 
3. T. rostrata — Deltoid, ventricose ; anterior side produced, pointed ; pos- 
terior depressed, round. — Sower. Min. Conch, t. ccxcv. f. 3. — Lower Oolite. 
4. I. sulcata. — Orbicular, deeper than wide, longitudinally sulcated, pear- 
ly ; beaks remote. — Sower. Min. Conch, t. ccxcv. f. 4. — London Clay. 
5. I. concentiica — Transversely elongate, heart-shaped, concentrically sul- 
cated ; shell thin — Sower. Min. Conch, t. ccccxci. f. 1 — Lower Oolite^ 
6. I. ohlonga — Oblong, anterior side short, ventral and dorsal margins 
nearly parallel, and almost straight ; rounded retrally — Sower. Min. Conch- 
t. ccccxci. f. 2 — In Carboniferous or Greywacke Limestone^ Cork. 
7 . 1. similis. — Transversely, rather oblong, ventricose, slightly flattened ; 
anterior side small, turned a little up ; edge of the base nearly straight. — 
Sower. Min. Conch, t. Dxvi. f. 1 — In Green Sand. Fragments of a shell which 
occur in the Suffolk Crag have been figured {Sower. Min. Conch, t. Dxvi. f. 2.) 
as resembling the recent Isocardia cor. They probably belong to the marine 
diluvium of the Modern Epoch, 
Gen. HIPPOPODIUM. — Shell equivalve, obliquely trans- 
verse ; valves inflated, sub-bilobed ; one rugged tooth at 
the hinge ; and the indication of a small lateral one under 
the ligament.” 
1,, H. ponderosum. — Gibbose, with irregular obtuse Vv^rinkled ridges. — 
Sower. Min. Conch, t. ccL— In Lias. 
Gen. CX. — CARDIUM. Cockle. — Beaks adjacent ; hinge 
with two umbonal teeth, and a remote lateral one in each 
valve. 
* Bibs armed with spines or tubercles. 
431. C. aculeatiim . — Shell tumid, thin, produced at the anal 
extremity, an angular bend behind the ligament, with 21 ribs. 
