Pvn H,i I'UitlS

LEPTON. 193
All the KelliidcB are of small size. They
are also
upstarts in a conchological point of view, none having
been known to Linne, or described by any writer until
near the close of the first decade of the present century.
But the family came into this country long before the
Conqueror. Many of our recent species flourished in
and the history of their
the time of the Coralline Crag ;
existence in these dark and remote ages has been duly
one
chronicled. They now inhabit both hemispheres :
kind of Montacuta is found in the Arctic seas, and
are diffused over all the
species of that and other genera
vast tract of sea which lies between Cape Horn and
" The gulfy coast of Norway ironbound."
A peculiarity of this family consists in some of them
being viviparous. This is certainly the case with Montacuta
substriata, Lasaa rubra, and Kellia suborbicu-
laris. The Sphariida? resemble these members of the
present family in the above-mentioned peculiarity, as
well as in shape.
Genus I. LEPTON * Turton. PI. IV. f. 7.
Eodt voluminous : mantle protruded, and furnished with
long tentacular cirri : foot capable of being expanded
disk -like form.
into a
Shell roundish-oval or triangular : cartilage small : hinge
furnished with a single cardinal tooth and two strong lateral
teeth in each valve.
This genus closely resembles Galeomma ; but the
animal has no ocelli, the shell does not gape in front,
and the hinge exhibits a goodly array of cardinal and
lateral teeth. Mr. Clark has, by his careful observations,
completely dispelled the commonly received idea
* Tliin as a scale.