199 TRITONIDA. 
necting link between the two groups, but certainly cannot be 
safely removed from the vicinity of the latter, to which it is not 
only allied by its operculum (which is entirely different from that 
of Dolium), but so closely by the shell in some instances, that 
the assignment of the generic position is quite arbitrary. 
The Tritons are distinctly tropical in distribution, no species 
inhabiting the colder seas. The species are numerous and beau- 
tiful, presenting a great range of variation in size and color; 
one ‘species being almost the largest of gastropod mollusks, 
attaining a length of one and one-half feet, whilst others belonging 
to the Epidromoid section, do not exceed one-half inch in length. 
The cancellated forms are chiefly East Indian, and are dredged 
in sand in deep water; the West Coast of America species, 
covered with a rough epidermis, are obtained in sandy mud at 
from six to thirty fathoms depth. A number of species have a 
world-wide distribution, which is doubtless due to their free- 
swimming or pelagic larvee. These, unlike the Murices, but like 
the Purpure, are very different at first from the adult both in 
animal and shell, undergoing a metamorphosis at a period subse- 
quent to hatching. 
I adopt the well-known name Triton in preference to the pre- 
viously given Tritonium of Cuvier, believing that the interests 
of science are best conserved by keeping the nomenclature as 
stable as possible. Triton has been used in other departments 
of zoology, but so have many other generic names, which are 
nevertheless accepted without question. 
Reeve says: ‘The Tritons are shells of much more solid 
structure than the Murices or Ranelle, and of much more simple 
growth. They are not furnished with any spines nor have they 
any ramified branches like the Murices; the rude manner in 
which the whorls are convoluted seems rather to indicate that 
their animal inhabitant, though possessing abundant power of 
calcification, is of somewhat sluggish growth. The epidermis of 
Triton is often remarkably thick, hairy and bristly, and is some- 
times accompanied with small tufts of bristles. Another curious 
peculiarity in these shells is the structure of the apex ; it appears 
in numerous instances to be formed of horny substance, thinly 
plated with shelly matter, and it is not an uncommon thing to 
find examples in which the calcareous plating is worn off so as 
to expose the horny cast underneath. The columella of the 
Tritons is generally covered with a bright coat of wrinkled 
enamel, and the outer lp becomes thickened in a manner 
exceedingly curious; upon arriving at maturity the lip curls 
under so as to form a deep, broad channel or gutter, and this is 
then filled up to form the thickened lip. The varices are all 
constructed in the same manner, each forming for a time the 
margin of the aperture; they are destined, it is conjectured, to 
