460 MANUAL OF THE MOLLUSCA. 
MontacuTta, Turton. 
Nedicated to Colonel George Montagu, the most distinguished 
of the earlier English malacologists. 
Type, M. substriata, Pl. XIX., Fig. 13. 
Shell minute, thin, oblong, anterior side longest ; Goes line 
notched ; ligament internal, between 2 laminar, diverging 
teeth (with a minute ossicle. Lovén.) 
Anima’ with the mantle open in front; margins simple; 
siphonal orifice single; foot large and broad, grooved. 
The Montacutce moor themselves by a byssus, or walk freely ; 
M. substriata has only been found attached to the spines of the 
purple thheart-urchin (Spatangus purpureus) 11 5—90 fathoms. 
M. bidentata burrows in the valves of dead oyster-shells. 
Distribution, 3 species. United States, Norway, Britain, 
Aigean. ° 
Fossil, 2 species. Pliocene—. Britain. 
LEPTON, Turton. 
Etymology, lepton, a minute piece of money (from /eptos, thin). 
Synonym P Solecardia (eburnea), Conrad, Lower California. 
Type, L. squamosum. Pl. XIX., Fig. 14. Fig. 256. 
Shell sub-orbicular, compressed, smooth, or shagreened, a 
little opened at the ends and longest behind; hinge-teeth 0.1 
or 1.1 in front of an angular 
cartilage notch; lateral teeth 
2.2 and 1.1. 
. Animal with the mantle (m) 
open in front, extending beyond 
the shell, and bearing a fringe 
of filaments, of which one in 
front (t) is very large; siphon 
(s) single, gills two on each side, 
separate ; foot ( f). thick, tapering, heeled and grooved, form- 
ing a sole or creeping disk. (Alder.) 
Sub-genus. Scintilla (Cumingi), Desh. 1856. Small shells 
resembling Lepton; minutely punctate; ligament internal, 
oblique; hinge-teeth 1. 2; posterior laterals 1. 2. Distribu- 
tion, 37 species (?), Philippines, North Australia, Panama. 
Distribution, 50 species. United States, Britain, Spain. 
Laminarian and Coralline Zones. 
fossil, 5 species. Pliocene—. United States, Britain. 
Fig. | 256. Lepton. 
