ANATOMY OF THE LEMUROIDEA. 9 
Chetromys* differs little, if at all, from Galago in the configuration and development 
of the external ear; except, it may be, in the relatively diminished size of the expanded 
fossa of the antihelix, and in the shallower and broader condition of the pit (=2*) above 
the antitragus. In the general appearance and position of the ear-folds the Aye-Aye 
resembles Lemur; but size differentiates the one from the other. 
3. The Extremities (Manus and Pes). 
There is a striking diversity between the development of the various digits in Man 
and Apes and their condition in Lemuroids, 7. e. the Anthropoidea and Lemuroidea. 
While in the former group the four ulnar or peroneal digits are, without exception, 
well developed, the inner, 7. ¢, radial or tibial digit, is subject to great variation, the 
pollex being quite rudimentary in Colobus and Ateles, while the hallux is diminutive in 
the Simia and Hapale. 
In the second group, on the other hand, the innermost digit, whether of manus or pes, 
is invariably well developed; but some abnormality continually crops out in the index 
or third digit of one or other extremity,—for example, the claw-like nail so constant 
in the index of the pes, and in the index and third digit also in Tarsius, the extreme 
attenuation of the third digit of Cheiromys, the general shortness of the index of the 
manus and its rudimentary condition in Arctocebus and Perodicticus. 
With regard to the fleshy pads of the palms of the hands we find the conditions to 
be as follows :— 
In Lemur (woodcut, fig. 5) one very large pad, the largest of all (no. 1), occupies the 
position of the ball of the thumb in Man, In front of this a very considerable pad 
(no. 2) occupies the base of the root of the index. Another, much smaller, pad (no. 3) 
is placed behind the roots of the third and fourth fingers. Another pad, not quite so 
large (as that belonging to the index), (no, 4) is placed at the root of the fifth digit. 
Indistinctly below the last-mentioned pad, running along the ulnar border of the palm, 
are two others placed anteroposteriorly, one behind the other (nos. 5 and 5*). The 
anterior of these two (no. 5) is the smallest of all the pads. The posterior one (no. 5*) 
is of nearly the same size as that at the root of the index. 
In Galago (woodcut, fig. 7), instead of one large pollicial pad there are two (nos, 1 and 
1*) (separated by a deep furrow), placed one in front of the other. The anterior of these 
(no. 1*) is the larger, and projects freely forwards between the pollex and index. 
The indicial pad of Lemur is represented by a very large one in Galago (no. 2), the 
anterior end of which projects between the second and third digits. The rest is as in 
Lemur, except that but one single pad (no. 5) appears to represent those two which in 
Lemur occupy the posterior part of the ulnar border of the palm. In Microcebus 
myoxinus Dy. Peters’ says there are five palmar eminences, the three smaller at the 
Owen, Trans. Zool. Soc. vol. v. p. 43, and pls. iv.—xviii. Also Peters, ‘Cheiromys,’ Berlin, 1866, p. 82, 
and pl. i. fig. 1. * Reise nach Mossambique, p. 15, 
VOL. VII.—PART I. C 
