632 MR. ST. GEORGE MIVART ON THE CRANIA  [Noy. 22, 
mostly present, but sometimes absent. There is no conspicuous fora- 
men for the internal carotid (as there is in the Galagos and Slow 
Lemurs) plainly visible in the basis cranii. The foramen rotundum 
is very close to the sphenoidal fissure, but is normally distinct from it. 
The Vidian foramen* is obvious at the back of the orbit. The angle 
of the mandible is not produced downwards as well as backwards. 
The upper incisors are always subequal, and the three upper pre- 
molars have each only one large external cusp; moreover the verti- 
cal extent of the first upper premolar falls more or less short of that 
of the second. This is the case in even aged skulls, and consequently 
is certainly no¢ the effect of immaturity, as was suspected to be the 
case in Microcebus smithii and M. pusillus, the only forms of those 
we have yet reviewed in which the first upper premolar is shorter 
than the second. The three upper molars have each two pretty 
equally developed external cusps, one large antero-internal one, and 
a very large internal cingulum, which is most developed at the ante- 
rior part of the inner side of each tooth, Of the three molars, the 
third} is the smallest (the first and second being subequal), but it 
exceeds the third upper premolar in size. There isa great difference 
between this latter tooth and the first upper molar ; but this difference 
is most marked when the teeth are viewed from without, when the 
third premolar, though, as has been said, it has but one external cusp, 
is seen (Lemur in this differing from Galago) to surpass the first 
molar in vertical extent. 
In the lower jaw the incisors never equal in length the mandibular 
symphysis. The three premolars have each only one large external 
cusp (the molars, again, having two) ; and the second premolar is not 
quite equal in height to the third, which surpasses in this respect the 
first lower molar. The last inferior molar is always smaller than the 
two preceding ones. 
I have been quite unable to detect any cranial or dental characters 
which would justify a subdivision of the genus Lemur. The dorsal 
vertebra are either twelve or thirteen in number; in the first case 
there are seven lumbar vertebrae, in the other there are sixt. Ac- 
cording to Dr. Peters, the gall-bladder has its base turned towards 
the back. 
The order of succession in which the permanent teeth come into 
place in this family appears to be subject to some variation. Unfor- 
* The existence of the “ Vidian canal” in Apes and other Mammals, and its 
distinctness from the so-called Vidian canal of Cuvier (mentioned in ‘ Lecons 
d’ Anat. Comp.’), was pointed out by my lamented friend Mr. H. N. Turner, Jun., 
in the Proceedings of the Zoological Society, 1848, p. 72. I have noticed it, 
amongst the Lemuride, in Loris, Nycticebus, Perodicticus, and Galago, as well 
as in Lemur. 
+ This, together with the proportions of the cingulum, tells against the Lemu- 
rine affinity of the fossil described and figured by Riitimeyer, in his ‘ Hocane 
Saiugethiere,’ under the name Cenopithecus lemuroides. I know no species of 
the Lemuride in which the last upper molar is the largest. In Tarsus the last 
upper molar is very much the same size as the second. 
t In the second edition (1835) of the ‘ Legons d’Anat. Comp.,’ tome i. p. 178, 
a Lemur (autre Maki) is mentioned as having 12 dorsal, 8 lumbar, and 3 sacral 
vertebrae. 
