Ve 
A Fish-Eating Rodent. 
VERY interesting new Mammal has recently been received at the 
British Museum, in the form of a Fish-eating Rat from the 
mountain streams of Central Peru. The animal is of about the size 
of a common house-rat, but has a flattened head, strong and 
numerous whisker-bristles, and very small eyes and ears, characters 
which give it a striking resemblance in its physiognomy to some of 
the aquatic genera of the Insectivora and Carnivora, such as Potamo- 
gale, Myogale, Lutva, or Cynogale. Its swimming powers are evidently 
very great, as is shown, among other things, by its broad, webbed and 
strongly-ciliated hind feet, far better developed for this purpose than 
are those of the ordinary swimming Muridz, such as our English 
Water-vole, whose simple vegetarian diet does not necessitate the 
development of any exceptional swimming powers. In colour, like 
the common Water Shrew, it has a dark upper side with a whitish 
belly, and has a markedly bicolor black and white tail. 
The chief interest of the new form centres in the fact of its 
being wholly a fish-eater, and in its having in connection therewith its 
incisor teeth modified for catching a slippery, active prey by the 
development of their outer corners into long sharp points, and its 
intestines altered by the reduction almost to mi/ of its coecum, an organ 
in vegetarian Muridze always of great size and capacity. The stomach 
of the single specimen obtained contains fish-scales, recognised by Mr. 
Boulenger as those of Tetvagonopterus alosa,a fish whose average length 
is about six inches. 
This animal represents quite a new departure in Rodent life- 
history, for although it is now perfectly well known that the North 
American Musquash (Fiber zibethicus) occasionally feeds on fish 
caught by itself, yet there is no other Rodent which, as in the case of 
Ichthyomys stolzmanni, as it is proposed to term the new form, wholly 
lives on fish, to the exclusion of a vegetable diet. 
The general relationships of Ichthyomys are clearly with the ordi- 
nary South American Muride, perhaps more especially with those 
of the Habrothrix group, and there is certainly no direct connection 
with Fiber. 
The type and only known specimen of this interesting form was 
obtained by the Polish collector, Mr. J. Kalinowski, at Chanchamayo, 
Central Peru, in the course of 1891. 
OLDFIELD THOMAS. 
