BIVALVIA. 129 
L. pygmaea in being rather more pointed or angulated at the siphoni-lateral margin, with 
a less elevated umbo, and there is a rather large cartilaginous area and a narrower hinge, 
the shell also is more tumid. 
The Highgate variety of Z. prisca is most probably NW. minima of ‘Min. Conch.,’ 
t. 192, fig. 9, which Mr. Sowerby suspected might be the cast of another species. 
7. Leva partim-striata, S. Wood. Tab. XVII, fig. 1, a—e. 
Nucuna srriava, var. J. Sowerby. Trans. Geol. Soc., 2nd ser., vol. v, pl. viii, fig. 12, 1834. 
Spec. Char. L. testa elongato-ovatd, oblatd, tumidd, tenui, subequilaterali ; pedi- 
regione convexd, siphoni-regione longiore et obtuse rostratd ; in medio longitudinaliter 
costata vel sulcatd ; utrinque levigatd ; umbonibus prominulis. 
Shell elongately ovate, oblate, tumid, thin, inequilateral; pedal region convex ; siphonal 
region the longer, laterally compressed, and obtusely rostrated ; central region longitu- 
dinally ridged, with both extremities smooth ; beaks slightly prominent. 
Length, rd of an inch. 
Localities. Clarendon, Highgate, Potter’s Bar, Haverstock Hill, Alum Bay (Zdwards), 
Hampstead Heath (Wetherel!). 
Although this species appears to have had an extensive geographical range, it is 
nowhere found in abundance. 
The species to which it approaches nearest is WV. amygdaloides, Sow., from which, 
however, it differs in being only partially covered with ridges, and it is also more inflated 
and more obtuse. The ventral region is covered with ridges, but the pedal, as also the 
siphonal sides, are quite smooth. he shell is tumid only in the pedal and central 
regions ; and compressed on the siphonal side. 
8. Lepa propinava, 8. Wood. Tab. XX, fig. 2. 
Spec. Char. L. testé minutd, ovato-subtrigonuld, convewiusculd, sub-inequilaterali, tenut, 
levigatd ; pedi-regione elongato-ovatd vel semi-ellipticd ; siphoni-regione subrostratdé et 
angulatd ; umbonibus depressis, utringue sub-equaliter declivis, lunuld anoque vie perspicuis. 
Shell small, ovately triangular, slightly convex, nearly equilateral, thin, and smooth; 
pedal side elongately ovate or semi-elliptical ; siphonal side obtusely rostrated or dorsally 
angulated; beaks depressed, with nearly an equal slope on each side ; lunule and corselet 
scarcely perceptible. 
Length, 3ths of an inch; height, half the length. 
Locality. Colwell Bay (Ldwards). 
