﻿AND SPECIES OF THE FAMILY UNIONIDJE. 299 



Unio scobinatus. PI. 26, fig. 13. 



Testa plicata, transversa, in medio compressa, valde inaequilaterali, postice angulata, ad basim emarginata; 

 valvulis subcrassis ; natibus parvis, prominulis, ad apicem undulatis ; epidermide viridi et lutea, minute 

 striata ; dentibus.cardinalibus obliquis, compressis ; lateralibus praelongis, in utroque valvulo 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. 

 #«&.— Siam. 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 1-3 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 minutely striate • 

 umbonial slope subangular ; cardinal teeth oblique, short, crenulate, double in both 

 valves ; lateral teeth very long, double 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. In o-alls 

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

 possession 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 beino- a 

 variety only of Dr. Gould's crispatus, 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 smaller, 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 scobinatus 

 is pearly white. In outline scobinatus approaches phaselus herein described, which is 

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



