43 Mr. J. W. Williams on a new Species of Ampullaria. 
and its breadth (taking the body-whorl) 48 millim. The 
general shape of the shell is globoso-conoidal, the body-whorl 
in the region of the peritreme being considerably swollen, but 
compressed laterally in that part where it passes into the 
penultimate whorl. There are five whorls. The spire is 
very short (12 millim.) in comparison with the rest of the 
shell, and its apex is obtuse. The suture between the body 
and the penultimate whorl and also between this last and the 
antepenultimate whorl is deeply and triangularly channelled 
(hence the specific name of canaliculata proposed for it). The 
nucleus is of a light rufous colour. The general body-colour 
is of a dull yellow ish green (similar to that of our English 
Paludina vivipara, Linn.) and is marked on the body-whorl 
by fourteen linear brown spiral bands, by four on the penul- 
timate, and by three on the antepenultimate whorl. The 
periostr acum is strongly marked with closely placed longitu- 
dinal striz continuous from whorl to whorl over the sutures ; 
the transverse striz are much finer and wider apart than are 
the longitudinal strie. The inner lip is reflected upon the 
body-whorl, and behind a ledge of it can be seen a large, 
deep, and obliquely placed umbilicus. The aperture is of an 
ovoidal shape, with a transverse diameter of 34 millim. and a 
longitudinal one of 45 millim. The peritreme is of a car- 
neous colour, and this is continued on the inside of the body- 
whorl for a distance in one specimen of 14 millim., behind 
which the internal layer of the shell is coloured a chocolate- 
brown. The banding of the shell is visible on looking into 
the shell from the aperture. The operculum is chitinous (as 
is the case with nearly all New-World species) and somewhat 
of a reniform shape, its narrower end being placed in the 
aperture upwards. It is well marked by concentric striz and 
the nucleus is placed excentrically, near to what corresponds 
to the hilum of its reniform shape. On its outer aspect the 
nucleus is placed on a depressed area, which corresponds to 
a circumscribed elevation on its inner aspect. ‘The whole of 
the periostracum is glossy and the whole shell translucent. 
The umbilicus discloses a part of the penultimate whorl. 
The specimens from which I have given the above descrip- 
tion were collected by Mr. George in October last. They were 
sent to me on May 8th of this year, having been brought by 
him from Buenos Ayres, and the most interesting part of it 
is that one of the shells contained an animal which, on extrac- 
tion, showed evidence of very recent death, and which, 
although giving off no fetor, was unfortunately not quite in a 
fit state for systematic dissection. Mr. Geor ge brought the 
shells over packed with Unios and Heliz ( Macular ia) punctata, 
