NEW I'KESII WATKK AND LAND .SllKLLS. 1') 



Unio scouinatus. pi. 20, tig. 18. 



Tests. pHcatst, transversa, in medio compressa, vald6 inacquilaterali, postic6 angulata, ad basim emarginatS; 

 valvulis subcrassis; natibus parvis, prominulis, ad apiccm undulatis ; epidermide viridi et lutea, minuti? 

 striata ; dentibus cardinalibus obliquis, compresses ; latcralibus praclongis, in utroque valvule duplicibus 

 subrectisque ; margarita alba et iridescente. 



Shell plicate, transverse, compressed in the middle, very inequilateral, angular be- 

 hind, emarginate at base ; valves rather thick ; beaks small, somewhat prominent, 

 undulate at the tip ; epidermis green and yellow, minutely striate ; cardinal teeth 

 oblique, compressed ; lateral teeth very long, double in both valves and nearly straight ; 

 nacre white and iridescent. 



Proc. Acad. Nat. Sci. Vol. 8, p. 93. 

 Eah.— Slum. T. R. Ingalls, M. D. ; S. R. House, M. D. 



My cabinet, cabinet of Dr. Ingalls and W. A. Haines. 

 Diam. -5, Length -6, Breadth 1-8 inch. 



Shell folded, transverse, compressed in the middle, very inequilateral, angular be- 

 hind, emarginate at base ; substance of the shell rather thick ; beaks small, a little 

 prominent, undulate at tip ; folds green, beautifully arranged over the whole disk, 

 acutely angular over the middle, on the umbonial slope enlarging from the beaks to 

 the posterior margin, where they are nearly parallel ; ligament short and thin; epider- 

 mis yellow, the raised folds being always green, transversely and minutelj' striate ; 

 umbonial slope subangular; cardinal teeth oblique, short, crenulate, rfoM&/e in hoih 

 valves ; lateral teeth very long, douhle in both valves, enlarged at the posterior end and 

 nearly straight; anterior cicatrices distinct; posterior cicatrices confluent; dorsal 

 cicatrices placed on the under side of the plate, posterior to the cardinal tooth ; cavity 

 of the shell shallow ; cavity of the beak rather shallow and subangular ; nacre white 

 and iridescent. 



Remarks. — This very beautiful Siamese little species was first sent to me by Dr. Ingalls, 

 of Greenwich, N. Y. Several specimens of diiferent sizes have since been put into my 

 posses.sion by Mr. Haines, to whom I am indebted for so many new species from this 

 part of Asia. On receipt of Dr. Ingalls' specimens I had some doubts of their being a 

 variety only of Dr. Gould's crl^patm, but this doubt was dispelled on receipt of Mr. 

 Haines' specimens. It belongs to that group of which gratiosus, Phili., may be con- 

 sidered the type. It certainly is nearest allied to crispatus, but may be distinguished 

 by its being smallei', more transverse, having larger folds, and these thickly covering 

 the whole disk, except on the last growth of old individuals ; also in being compressed 

 over the middle, and emarginate at base and in the duplex form of the lateral teeth. 

 The crispatus is disposed to be yellowish in the cavity of the beaks, while scohiiiatus 

 is pearly white. In outline scobinaUui approaches phaseliis herein described, which is 

 rather smaller, and is a polished shell with few folds. They both have the duplex 



