A NO DON elongatus, 



Lengthened Anodon. 



Generic Character. — See PI 96. 



Specific Character. 



A. testa transversim ohlongd, crassd, aiitici compressd, extrtmitate 

 ntrdque rotundatd; umbonibus xalde promincntibus, crassis ; 

 laniind cardinali coniexd. 



Shell transversely oblong, thick, anteriorly compressed, both 

 extremities rounded ; urabones very prominent, thick ; hinge- 

 plate convex. 



iHis extremely rare shell bears not the least resemblance 

 to any which Lamarck has described, or with which I 

 am acquainted. It was formerly in the late Mr. Forster's 

 collection, and is now in the possession of Mrs. Mawe. Its 

 form is like that of U/iio ovatus (Mj/a ovata of Montague), 

 but it is a much thicker and stronger shell ; tlie posterior 

 end is greatly compressed, but round ; the umbones convex, 

 remarkably thick, and deeply eroded ; the inside pearly 

 and iridescent, with a strong flesh-coloured tinge; the 

 ligamental or hinge-plate is perfectly smooth, and rather 

 convex ; the muscular impressions are deep. 



One valve of the specimen above alluded to (the only one I 

 have seen), is uncoated, and beautifully iridescent. Its country 

 is unknown — but I think it may prove a native of the 

 South American rivers. 



I'l. 176. 



