ginem ventralem extensd, in utrdque valvd : alt. -,%-, Uit. ^V* long. 

 1 poli. 

 Hab. in America Centrali. (Gulf of Dulce.) 

 This beautiful bivalve, rosy, transparent, and exquisitely nrought, 

 was found by Mr. Cuming, whose name it bears. It was obtained 

 from sandy mud, at a depth of twelve fathoms. 



Peliucid, and with the valves separated posteriorly likę the Ana- 

 tina;, with a crest so identical in form and structure with that of 

 sorae of the Mactrcs as to leave no doubt that this appendage is se- 

 creted in the šame manner as it is in the latter genus, — Cardium 

 Cumingii has the teeth and hinge of Cardium, and approaches so 

 closely in many points to Cardium bullatum or solenįforme and others 

 of that division, that, in the absence of all assistance vvhich might be 

 derived from investigating the anatomical structure of the animal, 

 I do not feel justified in separating it from them. 



Every one conversant vvith the subject has observed how very 

 variable the teeth are in the genus Cardium. We have an edentu- 

 lous Cardium [Card. Groenlandicum) , and another, a fossil species, 

 entirely destitute of lateral teeth on one side. Whether this genus 

 does not require revision is a ąuestion into vvhich 1 shall not novv 

 enter, Certain it is that it comprehends a very great variety of ex- 

 ternal form and structure. — W. J. B. 



Cardium PROCERUM. Card. testu ovatd, dorso acuminatiusculo, 

 pallidd,Jusco maculatd, antice rotundatd, postice subangulatd ; 

 costis radiantibus 25, anticis ąuatuor primis obsoletiuscuUs, re- 

 liguis prominentibus, postice angulatis, subrugosis ; medianis pla- 

 nulatis, utringue obtuse angulĮferis ; posticis antice angulatis ; 

 insterstitiis planulatis ; latere postico ringente, dentibus margi- 

 ncdibus validis ; epidermide Juscd : long. ti'3, lat.S'l, alt. 3'9 

 poli. 

 Hab. in America Centrali. (Real Liejos.) 

 Found in coarse sand in from four to six fathoms vvater. — G. B. S. 



Cardium Orbita. Card. testd obovali, pallescente, Jiilvo varie- 

 gatd; antice rotundatd, postice subangulatd ; costis radiantibus 

 42, anticis rotundalis, transversim costatis ; medianis utringue 

 granosis, granis posticis majoribus ; posticis postice granosis, 

 granis obliguis dentiformibus ; interstitiis, prtecipiie medianis, 

 profundis ; cardinis dente laterali antico maiiyno : long. 2-5, 

 lat. 2'3, alt. 3*3 poli. 



Hab. ad Insulam Annaa in Oceano Pacifico. ^ 



Found in fine coral sand on the reefs. 



Cardium planicostatum. Card. testd subcordįformi, palles- 

 cente, Juscojulvogue variegatd ; antice rotundatd, postice trun- 

 catd, rotundato-angulatd ; arece posticce medio prominulo ; costis 

 radiantibus 30, planulatis, acutimarginatis, anticis transversim 

 costellatis, posticis postice crenulatis, omnibus creberrime trans- 

 versim striatis ; umbonibus prominentibus ; depressione profundd 

 sub umbonibus anlice conspicud : long. l*^, lat. 1-2, alt. 1'6 poli. 



Hab. ad oras Americse Centralis. (Guacomayo.) 



Found in fine sand, at a depth of thirteen fathoms. 

 h2 



