CONCHIFERA. 489 
Sub-genus. Novaculina, Benson. N. gangetica, Pl. XXII., 
Fig. 10. Shell oblong, plain; epidermis thick and dull ; pallial 
sinus rather small; anterior pedal scar linear. Jistribution, 
India, China. In the mud of river-estuaries. 
Famity X VIII.—Myacip@. 
Shell thick, strong and opaque; gaping posteriorly ; pallial 
sine sinuated; epidermis wrinkled. Structure more or less 
distinctly cellular, with dark nuclei near the outer surface ; 
cartilage process composed of radiated cells. 
Animal with the mantle almost entirely closed; pedal aper- 
ture and foot small; siphons united, partly or wholly retractile ; 
branchiz two on each side, elongated. 
WS Ay 
iN) ine) ) 
yy Wh yy) wh Gs) 
Dy) 
Le i) 
is pa <r 
Fig. 265. Mya truncata, L. 3. Brit. (after Forbes.) 
Mya, L. Gaper. 
Etymology, myax (-acis), a mussel. (Pliny.) 
Synonym, Platyodon, Conrad. 
Types, M. truncata, Pl. XXIII., Fig. 1. M. Arenaria, 
Fig. 207, p. 396. 
Shell oblong, mequivalve, gaping at the ends; left valve 
smallest, with a large flattened cartilage process; pallial sinus 
Jarge. 
Animal with a small straight linguiform foot; siphons com- 
bined, covered with epidermis, partially retractile; orifices 
fringed, the branchial opening with an inner series of large 
tentacular filaments; gills not prolonged into the siphon; palpi 
elongated, free. 
M. anatina, Chemn. (Tugonia, Gray), West coast of Africa ; 
posterior side extremely truncated; similar cartilage-processes 
in each yalye. fossil, Miocene; Dax, and the Morea 
Distribution, 10 species. Northern Seas, West Africa, Philip- 
-pines, Australia, California. The Myas frequent soft bottoms, 
especially the sandy and gravelly mud of river-mouths; they 
range from low water to 25 fathoms, rarely to 100 or 148 
Y3 
