77 



appendicular ; dentibus lateralibus compressis, conspicuis : in- 

 terior calcarea ; sinu siphonali linguiformi, dimidiam longitudinis 

 testce attigente. Long. 5£ ; alt. 4 ; lat. 3 poll. Hab. Puget 

 Sound. 



No other species approaches this in size and capacity. 



Mesodesma munda. T. parva, solidula, convexiuscula, 

 ovato-triangularis, lsevis, epidermide stramineo induta ; natihus 

 posl-medianis,acutis ; margine dorsali vix arcuato, postice subitd 

 declivi ; latere antico angustato, acuto ; latere postico rotundato ; 

 margine ventrali valde arcuato : interior flavescens, cicatricibus 

 impressis: cardo dentibus validis instructus. Long. |; alt. § ; 

 lat. T 3 & poll. Hab. Mangsi Island. 



Distinguished from M. striata by its more compressed, less 

 angular form, its short, broad, rounded anterior end, there being 

 no angle except at the beaks, and by its smooth surface. 



Pandora cistula. Testa solida, alba, valde inequilateralis, 

 falciformis, antice rotundata, postice angustata, truncata : valva 

 plana tenuis, submargaritacea,concentrice undulata; margine dor- 

 sali subrecto, late inflecto, unidentato, dente brevi, elevato, trian- 

 gular! munito : valva concava solidior, ossea, tumida, postice 

 costato-angulata, edentula, fossa, ligamentali et costa. anticali 

 instructa ; margine dorsali concavo ; margine ventrali valde 

 arcuato. Long. 1£; lat. £ ; alt. 1 t l poll. Hab. East Pata- 

 gonia. 



More solid, more concave, and more elongated than any 

 species I am acquainted with. The upper valve of a small speci- 

 men from the same locality is semicircular, but more acute 

 anteriorly than posteriorly. 



Osteodesma bracteata. Testa parva, tenuis, transversa, 

 inequilateralis, ovato-falcata, ventricosa, margaritacea, epider- 

 mide fusco radiatim creberrime rugoso induta; latere antico 

 rotundato ; latere siphonali duplo longiore, triangulari, subad- 

 scendente, truncato ; margine dorsali recto ; margine ventrali 

 arcuato, sub-pendulo : interior deaurata. Long, f ; alt. |- poll. 

 Hab. Puget Sound. 



It is with some doubt that I separate this from 0. hyalina ; 

 but if its gilded nacre, its dusky colored, very numerously 

 folded epidermis, and the ventricose, pouched form of the pos- 



