614 MR. ST. GEORGE MIVART ON THE CRANIA_ [Nov, 22, 
genus of the family, except perhaps Microrhynchus, with which it 
also agrees in presenting no diastema posterior to the two teeth above 
mentioned*. When the grinding-surfaces of the upper teeth are 
looked at, the equality in size, from before backwards, of each dental 
series is absolutely greater than in any other genus of Lemuride. 
The upper incisors are subequal and very small, and are, as Dr. 
Gray has pointed out, placed one before the other on each side, so 
that the hinder one is quite hidden by the canine when the teeth are 
viewed laterally +. 
The upper canines are small; the first upper premolar on each 
side has but one cusp, but is more vertically extended than is the 
second premolar—a character by which Hapalemur differs from Lemur 
and agrees with the Galagos, Slow Lemurs, and others. 
The third premolar is exceedingly developed, being the largest 
tooth in the upper jaw, slightly exceeding the first and second molars 
in size. It quite resembles these in shape, both when viewed late- 
rally and from below. Each of these teeth has two pretty equally 
developed external cusps, and an internal one which represents the 
antero-internal cusp of a quadricuspidate molar. The postero-internal 
cusp is almost obsolete, as also the oblique ridge. The cingulum is 
very marked externally, but internally it is quite rudimentary. The 
last upper molar is also tricuspid, and intermediate in size between 
the second true molar and the second premolar, but very nearly equal 
to the former ; so that the three true molars and the third premolar 
are more equal one to another than even in Galago alleniit, and the 
greatest difference between any two contiguous grinding-teeth in the 
upper jaw is between the second and the third premolars. 
The lower incisors and canines, which are much as in Lemur, are 
rather short, and not by any means as long as is the mandibular sym- 
physis. 
The first lower premolar is but little developed vertically ; and the 
second has but one external cusp. 
The third premolar§ has two well-developed external cusps, and 
in size and form resembles the first inferior molar, which is quadri- 
cuspidate, as are the two teeth posterior to it—the four hindermost 
grinding-teeth below being subequal in size, like those above. As in 
the upper jaw, so also in the lower, the greatest difference between 
any two contiguous grinding-teeth is between the second and third 
premolars. 
Another well-marked and distinct generic form is that which Dr. 
Peters has described and figured under the name Microcebus myoai- 
* See De Blainville’s ‘ Ostéographie,’ Lemur, pl. 8. 
+ In Van der Hoeyen’s figure the hinder upper incisor is visible ; but, as before 
remarked, in his plate the skull is not represented exactly in profile. In M. 
Gervais’s two figures (Hist. Nat. des Mamm. p. 169), however, the second incisor 
on each side is represented as placed quite internally to the canine. 
t Noticed by Prof. Huxley, see ante, p. 324. 
§ In M. Gervais’s figure (p. 169) the antero-external part of the second and 
third premolars appears to be prolonged forwards outside the postero-external 
part of the tooth next in front. This is not the case in the British Museum 
skull. 
