17 



calcareous coating over the umbonal slope, on which are placed three 

 obliąue covered canals, formed by four radiating ridges, with another 

 coating of calcareous matter spread above them, leaving the aper- 

 tures distinctly visible at the anterior extremity. 



LiTHODOMus PLUMULA. TJt . testd L. canalifero simillimd, sed ex- 

 tremitate anticd minus obtusd; tegmine calcareo antico, crassiore, 

 atque in parietibus confertis, subparallelis ordinato ; parietibus 

 corrugatis et (plumulee haud dissimilibus) versus marginėm ven- 

 tralem et marginėm anticum utrogue latere radiantibus. Long. 

 0-75; lat. 2-35. 

 Hab. Panama, in Spondyli. Mus. Cuming, Hanley. 

 Were it not for the calcareous coating of the umbonal ridge, this 

 curious shell could scarcely be discriminated from the preceding 

 species. This coating is of a cellular structure, and is composed of 

 numerous rather elevated narrow ridges, ■which slope forward, and 

 80 radiate on either side from the middle as to remind us of a ruflied 

 feather. 



Mytilus granulatus. Myt. testd parvd, ovali-triangulari, tumidd, 

 crassd, radiatim costulatd; costis distinctis, angustioribus, rotun- 

 datis, granulatis, plerumque bifurcatis ; epidermide ockraceo- 

 flavescente ; margine cardinali brevi, conve.i:o ; antico valde ar- 

 cuato, dilatato ; ventrali subincurvato ; natibus maxime incumben- 

 tibus divaricatis ; angulo dorsali rotundato ; latere jjostico plajiulato i 

 valdi tumido ; superficie internd albd, submargaritaced ; margine 

 interno crenulis dentato. Long. 0"50 ; lat. O" 75. 

 Hab. Valparaiso, under stones at low water. Mus. Cuming, Met- 

 calfe, Hanley. 



A species easily to be distinguished by its narrow granulated ribs 

 (which become still narrovver on the flattened posterior slope) and 

 by the peculiarity of its beaks, ■which slope so greatly back as to 

 cause the shell to appear blunt and almost truncated at that part. 

 The hinge, as in most of this genus, is provided with two teeth in 

 one valve, and pne in the other. 



" A description of new species of recent Shells," chiefly from the 

 coUection of W. Metcalfe, Esq. 



Amphidesma scabrum. Amph. testd obovatd, convexd, solidd, sub- 

 eEįuilaterali, albd, lineis rubro-castaneis radiatd, concentrice lamel- 

 liferd ; lamellis brevibus, tenuibus confertis, interstitiis minutis- 

 sime longitudinaliter striatis ; latere antico subangulato, postico 

 rotundato ; margine ventrali arcuato, antici sinuato ; intUs pallide 

 aurantid, lunuld ,fQvedque ligamentali rubro-purpured. Long. 0*2 ; 

 lat. 21 poli. 



Hab. Boljoon, insula Zebu. Mus. Cuming, Metcalfe. 



Amphidesma Zebuense. Amph. testd obliąue ovatd, solidd, valde 

 ineeguilaterali, convexiuscuhl, albidd, )-adiis pallide rubris ornatd, 

 concentrice lamelliferd; lamellis brevibus confertis, interstitiis 

 strid elevatd concentricd, plerumęue notatd ; latere antico brevi, 



c 



