492 MANUAL OF THE MOLLUSCA. 
external; hinge-teeth 1 or 2; umbones strengthened inside by 
a posterior lamina; adductor (a, a’) and pedal impressions (p) 
separate, slightly impressed, posterior adductor bordered by a 
ridge; pallial line nearly simple, sub-marginal. 
Animal with short siphons, the branchial largest, surrounded 
at their base by 18-20 tentacles, generally reflected on the 
shell; mantle open in front; foot long, narrow, and slender. 
_ (M‘Andrew.) 
Distribution, 5 species. Norway, Britain, Mediterranean, 
Madeira, Borneo, China. 40—1450 fathoms. 
Fossil, 17 species. Neocomian—. Britain, Belgium, France, 
South India. 
Sub-genus? Hucharis, Recluz; Corbula quadrata, Hinds, 
Guadaloupe. Shell equivalve, obliquely keeled, gaping; beaks 
anterior ; hinge-teeth:1—1; lgament external; pallial line 
sunple; surface granulated. 
PanopmaA, Menard de la Groye. 
Etymology, Panope, a Nereid. 
Example, P. Americana, Pl. XXII., Fig. 12. 
Synonym ? Pachymya (gigas), Sby. Upper . Greensand. 
Britain, France. 
Type, P. glycimeris. Fig. 267. 
Shell equivalve, thick, oblong, gaping at each end; ligament 
external, on prominent ridges; 1 prominent tooth in each yalve; 
pallial sinus deep. 
Animal with very long, united siphons, invested with thick, 
wrinkled epidermis; pedal orifice small, foot short, thick, and 
zrooved below; gills long and narrow, extending far into the 
branchial siphon, the outer pair much narrower than the inner, ~ 
faintly pectinated ; palpi long, pointed, and striated. 
In: P. Norvegica the pallial line is broken up into a few 
svattered spots, as in Sawicava; the animal itself is like a 
gigantic Saxicava. (Hancock.) This species ranges from 
Ochotsk to the White Sea, Norway, and North Britain; it was 
formerly an inhabitant of the Mediterranean, where it now 
occurs fossil. (= P. Bivone, Philippi.) The British speci- 
mens haye been caught, accidentally, by the deep-water 
fishing-hooks. PP. Natalensis is found at Port Natal, buried 
in the sand at low water; the projecting siphons first attracted 
attention (doubtless by the strong jets of water they sent up 
when molested), but the shells were only obtained by digging 
to the depth of several feet. The Mediterranean species P 
g'ycimeris attains a length of 6 or 8 inches, 
