PROFESSOR OWEN ON THE AYE-AYE. 97 
of the medius in Chiromys, in like manner indicate a tendency to deviate from type in 
the hands and feet of this Quadrumanous family. 
Why the forefinger in both fore limbs should have been, as it were, amputated— 
reduced to a short stump—in one kind of Stenops, and why it should be much shorter 
than usual in others, is not intelligible in reference to any known use or peculiar 
application of the upper hand in that kind of Slow Lemur. 
The purpose of the probe-like middle finger is more readily discerned in the Aye-aye. 
The function of the large comb-like lower incisors in Galeopithecus, and that of the 
gouge-like strong incisors of Chiromys, have received explanation. Some might discern, 
in the greater length of the middle upper incisor of Propithecus and Tarsius as com- 
pared with that of the lateral incisor, and the reduction of the lower incisors to a 
single pair, a step in the transition from the Lemurine type of dentition to the extreme 
modification of that type in Chiromys. But all the surmises and guesses as to the condi- 
tions of such changes, all the attempts to explain how they were brought about—if they 
have been brought about—by still operative causes, are inadequate and unsatisfactory. 
The real knowledge which we possess of the Chiromys is limited to certain particulars 
of form, structure, habits, relations of structure thereto, likeness and unlikeness to other 
creatures, and geographical limitation. Far be it from me to imply that zoology may 
never know more than the nature and relations of the animal as it now exists. 
Although one of the greatest intellects has warned us of the futility of our finite 
endeavours to penetrate the mystery of the beginning of things, the attempts to dissi- 
pate that which still enshrouds the origin of species cannot but be fraught with collateral 
advantages to zoological science. 
DESCRIPTION OF THE PLATES. 
PLATE XIV. 
Female Aye-aye (Chiromys madagascariensis, Cuv.), half the natural size: from the 
animal living in the Gardens of the Zoological Society, October 1862. 
PLATE XV. 
Male Aye-aye, from the specimen transmitted, in spirits, by Dr. Sandwith, C.B., in the 
attitude of exposing the burrow of its favourite larval food: half the natural size. 
PLATE XVI. 
Front view of the same specimen : half the natural size. 
VOL. V.—PART II. ) 
