8o 



THE PROSIMIANS. 



extend so far only to the family of the 

 lemurs, and we must await future researches 

 in order to learn whether this character, 

 which entirely separates the Prosimii from the 

 Simiae, holds good also with reference to the 

 other families, which might well be doubted. 



All the Prosimii are tropical nocturnal 

 climbers, in which the general habits of 

 nocturnal animals are represented in different 

 degrees. While the true lemurs are to be 

 seen not infrequently even by day, the aye- 

 aye, the tarsier, the galagos, and the loris 

 move about only by night and sleep during 

 the day, rolled up in dark retreats. Many 

 are sleepy and sluggish in their movements; 

 but the power of leaping is exhibited in 

 different degrees of development in different 

 forms. This power is seen at its highest 

 in Tarsius and Galeopithecus, in the latter 

 of which it is assisted by an expansion of 

 the skin which stretches between the body 

 and the limbs, and acts as a parachute. 

 The structure of the limbs in different forms 

 harmonizes with these various powers of 

 movement. While the true lemurs, which 

 prowl about with a cat-like stealthiness, have 

 all the limbs of equal length, we see a 

 gradual shortening of the fore -limbs and 

 lengthening of the hind-limbs in the aye-aye, 

 galagos, and tarsier, and in the two latter 

 the power of leaping is increased by the 

 fact that the ankle- bones attain an extra- 

 ordinary length, so that the structure of the 

 foot approaches in some measure that of 

 birds. On the other hand, one might be 

 disposed to say that in Indris and Loris the 

 arrangement seen in Galeopithecus is in a 

 certain sense anticipated by the equal length- 

 ening of both pairs of limbs. 



Most of the Prosimii bring forth only one 

 young one at a birth, and this they carry 

 about with them for a considerable time after. 

 Still we are at liberty to presume that in some 

 species, in which the females have several 

 pairs of teats, several young ones are born at 

 once and are tended in holes of trees. 



We subdivide these animals according to 

 their geographical distribution, since a syste- 

 matic classification appears impracticable. 



THE 

 PROSIMIANS OF MADAGASCAR. 



The Lemurs (Lemurida). 



The lemurs (Lemurida) are animals which 

 may attain the size of cats, and which, while 

 bearing most resemblance in the general form 

 of body to the Mammalia of other orders, 

 are distinguished by their dentition. In the 

 upper jaw there are always two very small 

 incisors placed vertically and scarcely sepa- 

 rated by an interval in the middle line, and 

 these are followed by a large canine often 

 curved hook -wise or triangular in form. 

 There next follows a gap or diastema for 

 the reception of the canine of the lower jaw. 

 After that come three single -cusped pre- 

 molars, which, however, through the gradual 

 development of an internal process, approach 

 the form of the three molars. These last 

 have two exterior cusps and a rounded in- 

 ternal heel or process, so that they resemble 

 the so-called carnassial teeth of many carni- 

 vores. In the lower jaw three very narrow 

 but long incisors are inserted horizontally 

 very close to one another on each side. 

 Then follows the small canine, after which 

 come two single-cusped premolars, and then 

 three molars, on each of which there are 

 four more or less well-marked but not very 

 sharp tubercles, separated by a transverse 



2*1*3*3 



furrow. The dental formula is - 



3 ' l ' 2 ' 3 



= 36 teeth. The last molar is generally 

 the smallest in both jaws. 



The family we are now dealing with is 

 one rich in genera and species, and one in 

 which we may recognize, first, in the den- 

 tition a greater or less tendency to the use 

 of animal food, and, secondly, in the struc- 

 ture of the ankle an aptitude for leaping. 



