89 



truncato, ad apicem obtuso ; umbonibus ante-medianis, elevatis, 

 erosis ; dentibus cardinalibus obliquis, elongatis, compressis ; 

 dentibus lateralibus remotis, sub-arcuatis : margarita livido-albida. 

 Long. 2£ ; lat. | ; alt. 14 poll. Hab. Hunter's River, N. S. 

 Wales. 



Slender varieties have much the appearance of the more 

 expanded forms of U. lutulentus. It is more tumid, the beaks 

 more elevated and more central, the hinge more curved, the 

 cardinal tooth of the right valve more oblique and distinctly 

 bifid, the lateral tooth of the left valve less extensively cleft, and 

 I cannot find that it is ever nodular along the posterior slope. 



Unio verecttndus. T. tenuis, inequilateralis, transversa, ova- 

 to-oblonga, convexiuscula, luteo-olivacea ; margine dorsali recto ; 

 margine ventrali arcuato ; latere antico rotundato ; latere pos- 

 tico oblique rotundato; natibus prominulis, acutis, undulatis, 

 erosis: cardo exilis ; dentibus tenuibus longitudinalibus : marga- 

 rita salmonaceo-purpurea. Long. If; alt. 1£; lat. | poll. Hab. 

 Manila. 



Much like U. Bengalensis and TJ. foliaceus. In the former, 

 both ends of the ventral margin are angular, the posterior side is 

 dilated and angular at tip, and the interior is less bright red. 

 The form of this is rather elliptical than ovate. TJ. foliaceus is 

 smaller, thinner, compressed, and has a plumbaginous nacre. 



Unio dorsuosus. T. transversa, retrorsum ampliata, inequi- 

 lateralis, compressa, castanea ; latere antico circulari ; latere 

 postico oblique rotundato ; margine dorsali recto ; umbonibus 

 pro-eminentibus, antrorsum concentrice costato-undulatis, retror- 

 sum nodoso-fluctuatis : dente cardinali perobliquo, elongato, 

 compresso ; dente laterali recto : margarita ex albo-coerulescens, 

 livido ad umbones tincta. Long. 1£; alt. ■§■; lat. J- poll. Hab. 

 Eastern Asia ? 



Allied to TJ. Murchisonianus, Lea ; it is more widened poste- 

 teriorly, more compressed, not sinuate beneath, thinner. ^^^^_ - __ 



Avicula vidua. T. parva, tenuis, dolabriformis, vix obliqua, 

 per-inequilateralis, mutica, nitens, ex viridi purpurascens, deinde 

 nigra, albo obscure radiata: valva dextra planulata : valva sinis- 

 tra convexa,ecaudata : auricula parva, triangularis ; fissura parva, 

 superficial, edentata : margarita ex argenteo violacescens ; 

 12 



