75 



Panopjea generosa. Testa magna, ponderosa, calcarea, 

 sub-quadrilateralis, concentrice unduloso-plicosa, epidermide ru- 

 goso flavido induta, antics rotundata, postics truncata et valde 

 hians ; umbonibus submedianis, acutis, elevatis, undulatis : cardo 

 gracilis, dente elevato oblique triangulari instructus : cavositas ad 

 apicem profunda ; cicatrice musculari lato, bene impresso ; sinu 

 siphonali minime profundo. Long. 6 ; alt. 4 ; lat. 3 poll. Hab. 

 Puget Sound, Oregon. 



This large species stands by the side of P. Aldrovandi, but is 

 distinguished by the form of the anterior extremity. 



Mya pr^cisa. T. M. truncates, similis, calcarea, epidermi- 

 decorneo induta, ovata, antice rotundataet ventricosa, postice 

 angustata, compressa et truncata ; cardo dente trapezoideo, 

 latiore quam elevato, postice declivo instructus; linea palleali 

 angusta, crenata ; sinu siphonali profundo, arcuato ; cicatrice 

 anteriori elongato, falciformi. Long. 2^- ; lat. 1 ; alt. \\ poll. 

 Hab. Puget Sound. 



Differs from M. truncata in being more narrowed posteriorly, 

 more rounded anteriorly, more inflated at the umbonal slope, in 

 its narrow palleal impression and deeper siphonal sinus, and ' 



more particularly in having the tooth slope backwards. 



Mactra deluta. T. tumida, ovato-rotundata, hiantissima, 

 sordida, epidermide tenui deluto, oblique corrugato induta, con- 

 centrice undulata ; umbonibus submedianis, tumidis, incumben- 

 tibus, contiguis; margine dorsali utroque declivi ; margine ven- 

 trali rotundato; lateribus obtusis : cardinis fovea ligamentali 

 profunda; dente V-formi gracili, ramis inequalibus ; dentibus 

 lateralibus brevibus, trigonis, compressis ; sinu siphonali prope 

 centrum valvae obducto. Long. 1£; alt. If; lat. ly 1 ^ poll. Hab. 

 New Zealand. 



The external appearance is rather that of a rude Venus, and 

 has fewer angularities than any other Mactra. It is also peculiar 

 for its very wide gape. 



Mactra cuneola. T. parva, crassiuscula, rudis, ovato-cune- 

 ata, albida, epidermide stramineo induta, concentrice striata ; 

 umbonibus submedianis, tumidis, acutis, anteversis ; latere 

 antico angustato, subacuto ; latere siphonali breviori, tumidiori, 

 subtruncato : area cardinalis minima ; fovea ligamentali indis- 



