C R TiULA, 



i dla Bru 



Testa intequivalvis, intequilateralis, globosa re/ elongato- 

 globosa, plerumque crassa, solida, undique clausa. 

 Cardo dente centrali in utrdque valvd, foveold later ali 

 adjectd, ligamento inserto ; dente in valvd majore 

 (sinistra) conico, ascendente, recurvo, in valvd minore 

 (dextrd) cochleariformi subdepresso ,• dentibus latera- 

 libus nullis. Pallii impressio muscularis sinu parvo. 



Shell inequivalve, inequilateral, globose, or eloi 



globose, general]) thick ami solid, and everywhere 



closed. Hinge ; a solid central tooth in each valve 



with a ill i p pit on one sid< "i it for the n 



of the ligament; tenth in the larger or left valve 



conical, elevated or ascending, and hooked or curved 

 bind-.', in the smaller or right valve, spoon-shaped 

 and somewhat depressed ; no lateral teeth. Mus- 

 cular impression of the mantle exhibits a small 

 sinus 



The Corbula I d a- a g< im- by lirn- 



guiere in the Plal I cyclopedii M.thodique, 



are a small group of acephalous mollusks allied in some 

 degree to the Mya-, but whose real affinities do not 

 yet appear to lie correctly established. The sin lis oi 

 the Corbula? are remarkable for their solidity, ami pe- 

 culiarity of growth, the two valves of which they are 

 composed presenting a greater inequality of size and 

 I sculpture than those of any mollusks of the 



They arc for the most part marine, but some few like 

 the Cerithia an- found in fresh or brackish water. As 

 in that genus the freshwater species have been sepa- 

 rated under the title of Potomis, so in this they have bei D 

 distinguished by that of Potomya ; this modification of 

 habit doe- nut however, in my estimation, constitute a 

 generic difference, and 1 therefore propose to include 

 both the marine and freshwater species in one and 



Lamarck appears to have been acquainted with about 

 i ight species of Corbula; seven newones, collected by Mr. 

 Cuming along the western coast of South America, were 

 added to the genus by Mr. Sowerby in 1833, and about 

 double that number have been lately described by Mr. 

 Hinds, irom the collections made by himself in company 

 with Captain Belcher, and by Mr. Cuming, during his 

 researches amongst the Philippine Islands. One half 

 of the species above enumerated are therefore new to 

 science, and only three or four out of the whole number 

 have ever been figured. 



1. (Mus. Cuming.) 



\ \\-i i\. Corb. testd elongato-ovatd, gibbosis- 

 simd, postice altiore, antice acuminata, rostratd . 

 valvis leviter multicarinulatis, umbonibus centralibus. 



The nosed Corbi la. Shell elongately oval, very gib- 

 mi « I' il i lei iti d posteriorly, acuminated 

 and beaked anteriorly ; valves covered with nume- 

 rous fine small keels, umbones central. 



Soweeby, Pro. Zool. Soc, 1833. 



Hab. Xipixapi, Gulf of Nicoya (found in sandy mud at 

 the depth of ten fathoms) ; Cuming. 



The chief peculiarity of this shell is the beaked i \ 

 the anterior i xtremity. 



Specie- •_>. (Mus. Belcher.) 



Cobbula sulcata. Corb. testd subcordatd, valde intequi- 

 valvi, valvd dextrd parvuld, lavi; rnlni sinistra pro- 

 fundi sulcatd, multo complicatd , umbonibus gibbosis, 

 sub centralibus. 



The grooved Cobbula. Shell somewhat heart-shaped, 

 very inequivalve, right valve small, smooth ; left 

 valve deeply grooved, considerably lapping over; 

 umbones gibbous, nearly central. 



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

 p. 138. 



Huh. Senegal. 



The inequality in the growth of the valves is very 

 striking in this species, the upper valve being entirely 

 smooth, and only about half the size of the left valve, 

 which is very strongly grooved. 



Species 3. (Mus. Belcher.) 



Corbula biradiata. Corb. testd ovato-oblongd, postici 



rotundatd, antice angu/ato-aruminatd, longitudinaliter 

 striata, striis ennfertis, elevatis ; pallida, luttrihus 

 umbones versus suhunyulato-carinulatis, purpurascen- 

 tibus, radiis binis albis ornatis, area intermedia tte- 

 pressd, incarnato-tinctd. 



The double-rayed Corbula. Shell ovately oblong, 

 posteriorly rounded, anteriorly angulately acumi- 

 nated, longitudinally striated, strire close and nu- 

 merous; pale, sides slightly angularly keeled towards 

 the umbones, light purple, ornamented with two 

 white rays, the intermediate space being depressed, 

 and tinged with flesh- colour. 



Sowerby, Pro. Zool. Soc., 1833. 



August 1843. 



