309 



The following shells from the United States Exploring 

 Expedition were described by Dr. Gould : — 



AvicuLA VIDUA. T. parva, tenuis, dolabriformis, vix obliqua, 

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

 nigra, albo obscure rudiata : valva dextraplanulata : valva sinis- 

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

 superficialis, edentata : margarita ex argenteo violacescens ; 

 limbo lalo, nigro. Long. 1^; alt. f ; lat. y^^ poll. Hab. Feejee 

 Islands. 



In the early stages the color is grass green, then passing 

 through dark purple to coal black. It is remarkable for the per- 

 fect flatness of one valve. Its destitution of hinge teeth brings 

 it in Lamarck's genus Meleagrina. 



AvicuLA NIGRA. Tcsta mutica, inequivalvis, ecaudata, eden- 

 tula, fusca, antrorsum lobata ; valva dextra convexiuscula, pos- 

 tice integer, antice profunde emarginata ; auricula triangularis 

 crenulata : valva sinistra convexior, postice profunde emargin- 

 ata : margarita ex argenteo coerulescens ; limbo lato, fusco. 

 Ah. 2 ; long. If ; lat. ^ poll. Dredged at Singapore. 



More like A. margaritifera in form than any other, but is less 

 retuse, destitute of scales, and having its substance a plain pur- 

 plish black. It belongs to the section Meleagrina. 



AvicuLA MAcuLATA. Testa solidula, ventricosa, per-inequi- 

 lateralis, oblique rotundata, ecaudata ; margine caudali parum 

 producto ; extus calcarea, nigro radiata : auricula triangularis, cre- 

 nulata ; fiSsura profunda : margarita pallide aurea ; limbo cal- 

 careo lato, vitreo, albo et nigro radiate : margo cardinalis latus, 

 incrassatus ; dente cardinali papilliformi ; dente laterali brevi, 

 postice incrassato et deflecto, in valva dextra bifurcate ; cicatrice 

 muscular! reniformi, profundo. Long. If ; alt. If ; lat. f poll. 

 Hab. Tutuilla, Samoa Islands. 



The peculiar magnesian external coating, radiated with dark 

 purple, the golden nacre, and the porcelain-like marbled limbus, 

 make this a strongly marked species. 



AvicuLA FucATA. T. saccata, retrorsum obliqua, per-inequi- 

 valvis, scabra, rosaceo et flavido radiatim picta : auricula pras- 



