498 Mr. O. Thomas on small Mammals 
by the absence of the prominent white patch on the chin, a 
character generally fairly constant. 
The two species form rather a special group of the genus, 
but without specimens with less worn dentition it is difficult 
to make sure of their true relationship. 
12. Ctenomys knighti, sp. n. 
g. 336, 338, 357; 9. 328, 332, 335, 339, 340, 341, 345, 
360, 362. 
Allied to C. budini, Thos., of Jujuy. 
Size about as in budinz, the skulls of the males a little 
larger than male budini, but the females about the same. 
Colour above nearly as in that animal, or a little darker, 
rather paler than ‘ Mars brown” ; flanks, especially poste- 
riorly, distinctly clearer buffy, no such clearing of the general 
grizzled colour being present in dbudint; under surface 
uniform, without collar across throat, the whole distinctly 
more ochraceous than in budini, the ends of the hairs 
“* cinnamon-buft” or “pinkish cinnamon.” Muzzle, both on — 
top and sides of nose and tip of chin, blackish—no darkening 
being present in budin?. Tail slightly longer than in dudinz, 
the longest in four specimens of that species 70 mm., while in 
knighti it ranges from 73 to 84 mm. 
Skull of about the same general shape as in budini, or 
slightly more elongate, nasals rather narrower. Parietal 
region without trace of separate interparietals, even in the 
youngest specimen, these bones being present in all four 
examples of budin?. Palatine foramina longer, in a groove 
leading forward and enclosing the incisive fissures ; in budint 
the foramina end abruptly on the general surface of the 
palate and the fissures are quite distinct from them. Bullee 
of the same general shape, but rather larger, and, as viewed 
from behind, their smooth postero-superior portion is much 
more conspicuous owing to its being less covered over by the 
plastering bones of thie occipital series. 
Teeth as in C. budint, except that m* has a more obliquely 
elongate section at all ages. 
Dimensions of the type (male) and of an adult female 
(no. 340) :— 
Head and body 203, 180 mm.; tail 82, 74; hind foot 
36, 30; ear 7, 7. 
Skull: greatest median length 49°5, 44; condylo-incisive 
