420 Zoological Society. 



Monograph of Sph^nia, a genus of lamellibranchiate 

 MoLLTJSCA. By Arthur Adams, R.N., F.L.S. etc. 



In the unrhalled Collection of Mr. Cuming is a group of Bivalve 

 sliells, which appear to be neither Mya nor Corbula, but partaking of 

 the characters of each. The animal, which is also preserved in spi- 

 rits, resembles that of Corbula in having short united siphons, a small 

 compressed foot, and in the mantle being closed, with the exception 

 of an anterior elliptic opening ; the shells, however, have the hinge of 

 Mya, but do not gape at both extremities. The only genus, there- 

 fore, into which they resolve themselves is Spheenia of Turton, which, 

 with the hinge of Mya, gapes only at one end, and which moreover 

 is deprived of a long coriaceous siphon. Mr. Hanley has pubhshed 

 one species in the ' Zoological Proceedings,' under the name of Mya 

 semistriata, and !M. Deshayes another, under that of Corbula decus- 

 sata, in the ' Magazin de Zoologie,' 1844, and I had described a 

 third, under the name of Sphcenia Mindorensis, in the ' Zoology of 

 the Voyage of H. M.S. Samarang;' and to these I now add several 

 other large exotic species collected by Mr. Cuming. 



Sphcenia, Turton. 



Animal ovatum ; pallium antice clausum, prceter aperturam pro 

 pede parvo digitiformi sulco byssali instructo ; siphones con- 

 nati usque ad extremitates, orificia cirrata ; sipho analis val- 

 vidd tubulari membranaced extra orificium productd. 



Testa oblongu, incequivalva, incequilateralis, magis minusve postich 

 Mans ; Icevis, vel rugosa, epidermide tecta ; umbones incurvati ; 

 cardo dente laminari dilatato erecto in valvuld sinistrd, alveo 

 convenienti in valvuld dextrd ; ligamentum internum; impres- 

 stones pallii sinu parvo. 



Sph.enia Binghami, Turton. S. testd incequivalvd, inaquila- 

 terali, ovato-trigonaU, transversim concentrice sulcata, epider- 

 mide olivaceo tectd ; latere antico breviore, rottmdato, postico 

 lo7igiore, hiante, subtruncafo; i)nj)ressione pallii sinu subpro- 

 fundo, rottmdato ; dente cardinis valvultB sinistrcB postice sub- 

 sinuato. 



Hab. British islands. 



Sph^ni.a decussata, Deshayes, sp. S. testd ovato-oblongd, sub- 

 cequilaterali, postice truncatd, subrostratd, rostro basique ob- 

 lique carinatd, albd, striis longitudinalibus, transversisque 

 teniiissime decussata ; umbonibus magnis, oppositis ; dente car- 

 dinali magna, obliquo, compresso in valvd sinistrd, in valvd 

 dextrd foveold profundd, marginatd. 



Hab. Seas of Sumatra. 



SpHiENiA SEMISTRIATA, Hauley, sp. S. tcstd ttlbd, transversd, 

 ovali, ineqtiilaterali, concentrice striatd ; latere antico breviore, 

 valde convexo, Icevi; postico longiore, angustiore, truncato, ra- 

 diatim striata ; margine ventrali in medio sinuoso, postice an- 

 gidato, antice rotundato, 



Hab ? 



