OF NORTHUMBERLAND AND DURHAM. 187 
In slow streams, rather rare. Mill Race, Jesmond Dean. Near 
Stockton.—Mr. Hogg. 
Famity. Kenitapa, Forbes. 
105. LEPTON, Turton. 
1, L. convExuM, 7. s. 
Shell rather convex, transversely ovate, white ; covered with 
minute transversely oblong punctures ; hinge with the central 
tooth rather large, and the lateral laminz small. 
A single valve of a minute shell with these characters has oc- 
curred to us at Cullercoats. It is evidently a Lepton, and differs 
from ZL. sgquamosum in being rather more convex, in having the 
punctures of the surface oblong instead of circular, and in the 
greater proportional size of the tooth. These seem to indicate a 
specific distinction, but as the specimen is scarcely a line in dia- 
meter, and probably young, we cannot speak very confidently. 
The nucleus on the umbo is, however, so much smaller than that 
of LZ. squamosum, that we conclude it never attains the same size. 
106. KELLIA, Turton. 
1. K. suporpicunaris, Jfont. 
Mya suborbicularis, Mont. Test. Brit. 39, t. 26, f. 6. 
At the roots of Laminaria digitata, and other sea-weeds, un- 
der stones, and in the cavities of stones and old shells; not 
rare. 
This species is subject to great variety of size and form ; so 
much so, that we have thought more than one species might be 
confounded under the name, but we have failed to obtain any 
distinguishing character that can be depended upon as _ per- 
manent. Two varieties may be mentioned; the one thin, 
transparent, and with a delicate play of iridescent colours on 
the surface. This is generally found at the roots of tangle. The 
other, which is more common among rocks between tide- 
marks, is smaller, more orbicular, more strongly striated, and 
covered with an ochreous crust near the umbones. Intermediate 
forms occur. 
The animal of Kellia is very remarkable, and constitutes a new 
