ISOCARDIA.— Plate I. 



litis creberrimis, carinam super evanidis, carina area- 

 que postremd subtilissime striatis; lutescente-albd. 



The common Isocaedia. Shell oblong-ovate, somewhat 

 triangular, oblique, anterior side short, posterior elon- 

 gated, obtusely keeled; irregularly concentrically pli- 

 cately ridged, ridges very close, obsolete upon the 

 keel, keel and the extreme posterior area very finely 

 striated ; yellowish white. 

 Cardita Moltkiana, Bruguiere. 

 Isoeardia Moltkiana, Lamarck. 



Hub. China. 



Having identified the preceding species with the Chama 

 Moltkiana of Chemnitz, 1 have distinguished the present 

 h\ a name which indicates the abundant importation of 

 this once rare and highly prized shell. 



Species 3. (Fig. a and b, Mus. Cuming.) 



Isocardia cor. Isoc. testa globoso-cordatd, gibbosissimd, 



laevigata mil concentrice striata ; albidd, Uneis palUde 



fulvo-rufescentibus, trigono-undatis copiosissme tinctd, 



epidermide castaneo-fuscd, umbones versus detritd, in- 



ilntii ; iiin/ioni/nis interdnm sidjctrrulescentibit*. 



The heart Isocardia. Shell globosely cordate, very 

 gibbous, smooth or concentrically striated; whitish, 

 abundantly stained with pale fulvous red triangularly 

 disposed zigzag lines, covered with a chesnut brown 

 epidermis, worn away towards the umbones ; umbones 

 sometimes tinged with blue. 



Lamarck, Anim. sans vert. (Deshayes'edit.), vol.vi.p.445. 

 ( 'Jiama cor, Linnaeus. 

 Glossoderma cor, Poli. 

 Cardita cor, Bruguiere. 



Ha ) i !i last of Sicily, Mediterranean. 



This well-known species is more particularly characterised 

 by the fullness of the umbones, and by its globose and very 

 symmetrical structure. 



Species 4. (Mus. Cuming.) 



Isocardia Hibernica. Isoc. testa transverse cordatd, 

 gibbosd, laevigata out concentrice striata, umbonibus 

 parvis, subattenuato-contractis ; albidd, fulvo-rufes- 

 cente titictd, epidermide fused re/ olivaceo-fuscd, um- 

 bones versus detritd, indutd 



The Irish Isocardia. Shell transversely cordate, gib- 

 bous, smooth or concentrically striated, umbones 

 -mall, rather attenuately contracted; whitish, stained 



with fulvous red, covered with a brown or olive-brown 

 epidermis, worn away towards the umbones. 

 Isocardia cor (pars), auctorum. 

 Hal). Irish Sea ; Falmouth, Britain (dredged at depths of 

 from ten to forty fathoms) ; Cuming. 

 I am quite satisfied that the two shells, the one Medi- 

 terranean, the other British or Irish, which have been de- 

 scribed hitherto under the common title of Isocardia cor, 

 are distinct species. The former besides exhibiting the 

 usual indications of a warmer climate is of a full globose 

 form, whilst the latter though of equally large, if not larger 

 size, is of a transverse somewhat compressed form, with 

 the umbones much less involuted. These are not differ- 

 ences of mere local variation, but of specific consequence, 

 and are presented in all stages of growth ; indeed, they are 

 more conspicuous in young than in adult specimens. 



The propriety of this arrangement is singularly confirmed 

 by an observation in the second volume of the Zoological 

 Journal, made by the Rev. J. Bulwer, in reference to the 

 soft parts of these shells. After describing the habits and 

 anatomy of some examples of the Irish species, which the 

 reverend gentleman had preserved for some time alive in a 

 vessel of sea-water, he says, " Since committing the above 

 observations to paper I have seen the costly and elaborate 

 work of Poli, containing, among other investigations, an 

 account and anatomical drawings of the animal of the Iso- 

 cardia cor of the Mediterranean. On inspecting these a 

 considerable difference between the animals of the foreign •mil 

 Irish speck s is observable." 



Species •">. (Mus. Cuming.) 



Isocardia Lamarc kii. Isoc. testa oblongo-ovatd, obliqvd, 

 latere n,i lien brevissimo, postico subacuminato-elongato, 

 carinato ; irregulariter conct ntrice plicato-liratd, liris 

 carinam super tertninantibus, area posticd subtilissime 

 striata; lutescente-albd, postice rosea maculatd. 



Lamarck's Isocardia. Shell oblong-ovate, oblique, an- 

 terior side very short, posterior somewhat acuminately 

 elongated, keeled ; irregularly concentrically plicately 

 ridged, ridges terminating upon the keel, posterior 

 area very finely striated ; yellowish white, posteriorly 

 spotted with rose. 

 Isocardia Moltkiana? Encyclopedic Methodique. 



Huh. China. 



Distinguished from the Isocardia mlgaris l>\ it- more 



elongated form, by the concentric ridges terminating on 



the keel, and by its delicate rose-spotted painting. 



A 681 



