P E R N A. 



Plate IV 



Species 16. (Mus. Cuming.) 



Pebna costellata. Pern, testa elongato-Jlabellata, ra- 

 diatim Jkxuoso-Urida, concenirice laminatd, lamiuis 

 subremotis, acute Jimbriatis ; sordide alba, nigrescente- 

 purpureo tinctd. 



The finely-ribbed Perna. Shell elongately fan-shaped, 

 radiately flcxuously ridged, concentrically laminated, 

 laminae rather distant, sharply fimbriated ; dead white, 

 tinged witii dark purple. 



CoNiiAD, Journ. Acad. Nat. Sci. Pliil. vol. vii. p. 246. 



Hab. Society Islands. 



The lamina; of this species are frilled with small ser- 

 rate points. 



Species 17. (Mus. Cuming.) 



Pekna Limoides. Pern, testa mbelongato-flabellaid, con- 

 centrice fimbriato-laminatd, laminis planatis, subobso- 

 letis ; piirpitrascente. 



The Lima-like Peena. Siiell somewhat elongately fan- 

 shaped, concentrically fimbriately laminated, lamina 

 flattened, rather obsolete ; purplish. 



Hab. Moluccas. 



AUied to the preceding species in having the 

 festooned with small points, but difi^ering in substance and 

 general character. 



Pebn/ 



Species 18. (Mus. Cuming.) 

 FIMERIATA. Pern, testa elongato-oblongd, tenui- 



culd, compressd, concenirice fimbriato-squamatd, squa- 

 mis versus marginem subproductis ; antice alatd, aid 

 medio concavd et obscure liratd ; nigricante-purpured . 



The frilled Perna. Shell elongately oblong, rather 

 thin, compressed, concentrically fimbriately sealed, 

 scales towards the margin rather produced ; anteriorly 

 winged, wing concave in the middle and obscurely 

 ridged ; blackish-purple. 



Hab. Moluccas. 



A thin, dark-purple shell, in which concentric frills of 



produced scales form rather a conspicuous character. 



Species 19. (Mus. Cuming.) 



Pekna patibulum. Pern, testd elongatd, antice elongato- 

 alatd, plano-laminatd, laminis obscuris, aid medio ser- 

 rato-sulcatd ; semipellucido-purpured. 



The gibbet Perna. Shell elongated, anteriorly elon- 

 gately winged, flatly laminated, lamina; obscure, wing 

 serrately grooved in the middle; semitransparent 

 purple. 



Hab. ? 



Chiefly distinguished by its elongately produced wing, 

 of which the middle webbed portion is serrately grooved. 



March, 1858. 



