1864.] AND DENTITION OF THE LEMURIDZ. 619 
Of these two forms of so-called Cheirogalei, the C. smithii of Dr. 
Gray is, as he truly observes, ‘‘ very like” M. myoxinus, but for the 
smallness of the ears (relatively larger than those of C. typicus), the 
length of the feet agreeing. 
The dentition unfortunately cannot be well seen, but it agrees with 
that of M. myoxinus and M. minor in the preponderance of the inner 
upper incisors over the outer pair, in the three premolars having but 
one large external cusp, and in the great difference in size between 
the last premolar and the first molar; but Dr. Gray’s C. smithi dif- 
fers from them, and agrees with M. pusi/lus, in having the first upper 
premolar rather less vertically extended than the second ; and should 
this arise from immaturity, which (for reasons which will appear in 
speaking of the genus Lemur) I suspect to be the case, then there 
will probably be a considerable distinction in absolute size between 
the adult C. smithii and the species M. minor, two skins of which 
(labelled Galago minor) are, as before stated, in the national collec- 
tion. 
The other and considerably larger form, named C. typicus by Dr. 
Gray, is, in spite of its greater size, immature, the third lower grind- 
ing-tooth, on one side, being a deciduous one. The first upper pre- 
molar is remarkable, being, as Dr. Gray observes, “ large, conical, 
erect, like a small canine.”’ In this species also the tarsus seems to 
be relatively shorter. The upper incisors resemble those of M. my- 
oxinus and M, minor. 
I think it better to leave this form, provisionally, where Dr. Gray 
has placed it, namely, side by side with his C. smithii, and (as this 
last cannot, as far as I have yet had opportunity of observing its cha- 
racters, be generically separated from M. myoxinus, M. minor, and 
M. pusillus) to designate it Microcebus typicus, at the same time 
calling attention to the uncertainty of its position until its osteology 
and dentition are better known. 
The third form included by Dr. Gray in his genus Cheirogaleus 
is the Cheirogaleus milii of Geoffroy. This is the true type of that 
puzzling and troublesome genus, but unfortunately it is not repre- 
sented by either skin or skull in the British Museum. M. de Blain- 
ville has figured a side view of the cranium, showing the dentition*, 
as also has Dr. Dahlbom+. Judging from these illustrations, Cheiro- 
galeus appears to have considerable resemblance to Microcebus ; and 
should the alleged characters separating these two genera prove on 
examination to be worthless, and C. mz/i incapable of generic sepa- 
ration from JZ. pusillus, then the name Microcedus will have to dis- 
appear altogether in favour of the more ancient designation Cheiro- 
galeus. 
In the preponderance of the inner over the outer upper incisors, 
C. milii agrees with Microcebus ; but it differs, apparently, from M. 
* Ostéographie, Lemur, pl. 7. 
+ Studia Zoologica, vol. i. tab. viii. figs. 32 & 52a. Dr. Dahlbom’s figures 
are not very faithful: in fig. 82 the outer upper incisor is represented as larger 
than the inner, while in fig. 32 « the inner pair of upper incisors greatly exceeds 
the outer pair. 
