. 



243 MANUAL OF THE MOLLUSCA. 



L. Norvegica ranges from Norway to the sea of Ochotsk ; in 15 80 fms. 

 Fossil ? Miocene . Europe. (100 sp. L. Sil. . D'Orb.) 

 ? Entodesma (Chilensis) Phil. Shell thin, saxicava-shaped, slightly in- 

 equivalve and gaping, covered with thick epidermis ; hinge edentulous ; each 

 valve with a semi-circular process containing the cartilage. 



PANDORA. (Solander) Brug. 



Type, P. rostrata, PL XXIII. fig. ] 1. (Pandora, the Grecian Eve.) 



Shell inequivalve, thin, pearly inside ; valves close, attenuated behind ; 

 right valve flat, with a diverging ridge and cartilage furrows; left valve 

 convex, with two diverging grooves at the hinge ; pallial line slightly sinuated. 

 Outer layer of regular, vertical, prismatic cells, 250 times smaller than those 

 of Pinna (fig. 260). (Carpenter.} 



Animal with mantle closed, except a small opening for the narrow, 

 tongue-shaped foot ; siphons very short, united nearly throughout, ends 

 diverging, fringed ; palpi triangular, narrow ; gills plaited, one on each side, 

 with a narrow dorsal border. 



Distr. 13 sp. U. States, Spitzbergen, Jersey, Canaries, India, N. 

 Zealand, Panama: 4 110 fms. burrowing in sand and mud. 



Fossil, 4 sp. Eocene . U. States, Brit. 



MYADOKA, Gray. 



Type, M. brevis, PI. XXIII, fig. 12. 



Shell trigonal, rounded in front, attenuated and truncated behind ; right 

 valve convex, left flat ; interior pearly ; cartilage narrow, triangular, between 

 2 tooth-like ridges in the left valve, with a free sickle-shaped ossicle; pallial 

 line sinuated : structure like Anatina ; outer cells large, rather prismatic. 



Distr. 10 sp. N. Zealand, N. S. Wales, Philippines. 



MYOCHAMA, Stutchbury. 



Type, M. anomioides, PI. XXIII. fig. 13. 



Shell inequivalve, attached by the dextral valve and modified by form of 

 surface of attachment ; posterior side attenuated ; left valve gibbose ; carti- 

 lage internal, between 2 tooth-like projections in each valve, and furnished 

 with a moveable ossicle; anterior muscular impression curved, posterior 

 rounded, pallial sinus small. 



Animal with mantle-lobes united ; pedal opening and siphons surrounded 

 by separate areas ; siphons distinct, unequal, small, slightly fringed ; a minute 

 fourth orifice close to the base of the branchial siphon ; visceral mass large, 

 foot small and conical; mouth rather large, upper lip hood-like; palpi 

 tapering, few-plaited ; gills one on each side, triangular, plaited, divided by 

 an oblique line into two portions ; excurrent channels 4, 2 at the base of the 

 gills and two below the dorsal laminae (Hancock. An. Nat. Hist. 1853.) 



