“Ground-LHogs”’ or “Cane-Rats” of Africa. 391 
zygomatic breadth 50 ; interorbital breadth 25; upper cheek- 
tooth series 16°5. 
Hab. Lower Welle River, Congo, 
Type. Adult male. B.M. no. 7. 7. 8.192. Original 
number 64, Collected 2nd November, 1905, by Capt. G. B. 
Gosling. Presented by the Alexander-Gosling Expedition. 
This Cane-Rat is readily distinguishable from harrisoni 
and rutschuricus by its much paler colour. Being a female— 
the only adult female Chewromys in the collection,—any 
useful comparison with the skulls of other species is imprac- 
ticable, but the general shape of the skull is as in C. harrisont. 
In Thryonomys proper there seem to be very few diffe- 
rences, cranial or external, between specimens from the 
different districts, widely as the whole group ranges. 
Originally Temminck’s type was young and without 
locality, so that when, in 1831, a Sierra Leone specimen was 
identified with it by Bennett, that place was rightly accepted 
as the type-locality, and should be so treated. 
From this north-western form I can distinguish, as a sub- 
species, the common animal of the major part of Africa, from 
Uganda and the Upper Congo to the Cape, for which a name 
is available given by Peters solely as a synonym, but with 
enough description to make it valid. Then the forms of the 
Lower Niger and Angola may also be subspecifically recog- 
nized, making four in all. 
These may be briefly diagnosed as follows :— 
Thryonomys swinderianus swinderianus, Temm. 
Temminck, Mon. Mamm, i. p. 245 (1827); Bennett, P. Z. 8S. 1831, 
p. 111. 
Size rather less than in the common form. Colour more 
drabby brown, with less contrast between body and rump. 
Skull smaller, with a medium amount of development of the 
posterior intertemporal gutters. 
flab. N.W. Africa, trom Gambia to Northern Nigeria. 
Thryonomys swinderianus variegatus, Peters. 
Aulacodus variegatus, Peters, Reise Mossamb. p. 188 (1852). 
Aulacodus semipalmatus, Heugl. N. Act. Ac. Leop. xxxi. p. 5 (1864). 
Aulacodus calamophagus, de Beerst., Pousarg. Bull. Mus. Paris, 1897, 
p- 160. , 
Size largest. Colour very coarsely variegated, the head 
and fore-back brown, the rump more buffy. Skull large and 
