311 



angusta ad 5-crenata : intus sub-margaritacea. Long. 1^ ; alt. |- ; 

 lat. f poll. Hob. Feejee Islands. 



None of the species already described agree with this in color, 

 texture, or fornn. Its structure is very delicate and unresisting, 

 almost fibrous at its edge. 



Perna argillacea. T. solidula, mutica, compressa, elongata, 

 antice dilatata, postice subrecta, ex luteo alutacea, hie illic nigri- 

 cans ; apice adunco : fissura byssali angusta, lanceolata : intus 

 livescens : area cardinalis curta, obliqua, triangularis, sulcis obli- 

 quis ad 8 arata : fovea apicalis profunda. Long. 2^ ; alt. 3 ; 

 lat. t poll. Hah. ? 



The resemblance to the common P. epJiippium of the West 

 Indies is very great. It differs chiefly in the clay-colored exte- 

 rior, and in having the byssal instead of the opposite side dilated ; 

 the muscular scar is also smaller. 



Perna torva. T. rudis, crassa, inequivalvis, concentrice 

 lamellata, cinerea, obliqua, trapezoidea ; latere byssali dilatato, 

 semicircular! ; sinu byssali profundo; apice adunco ; latere pos- 

 tico rectilineari, obliquo, produclo ; raargine cardinali oblique : 

 area cardinalis triangularis, sulcis obliquis ad sex arata : marga- 

 rita ex argenteo-purpurascens ; limbo lato, retro dilalato. Long. 

 1^; alt. ]f ; lat. f poll. Hab. Sandwich Islands. 



The obliquity of this species and the small number of its car- 

 dinal sulci are among its most prominent characters. 



Perna eremita. T. fragilis, exaluminata, variabilis, dola- 

 brata, vulsellata, unguiformis, pectiniformis et omnimode dis- 

 torta, plerumque radiatim rugoso-striata et in junioribus rufo- 

 lineata; antrorsum plus minusve curvata : margarita argentea; 

 limbo corticali ampliato, foliaceo, stramineo, vitreo : margine 

 cardinali fere horizontali, 6-8 sulcato ; fissura byssali profunda. 

 Long. 2; alt. l^^^y ; lat. f poll. Inhabits Carlshoff" Island, Pau- 

 motu Group. 



This shell, though so variable as to elude all terms of descrip- 

 tion, is still very distinct from all others, in all its forms. It 

 seems to acquire its multiform shapes from the cavities in coral 

 where it resides. Young or well protected specimens are sculp- 

 tured by delicate radiating ramose ribs bearing minute scales. 



