340 INSECTIVORES. 



The Teneecs. 



Family CenteTIDM. 



Witli the curious-looking animal represented in the figure on the next page, 

 we reach the first member of a group of Insectivores, comprising four families, 

 which (litter from all those yet noticed in the characters of their upper molar teeth. 

 In all the preceding families the upper molar teeth have broad crowns, with their 

 cusps arranged somewhat in the form of the letter W. On the other hand, in 

 all those remaining for consideration, the crowns of these teeth are narrow, and 

 carry on their crowns only thi'ee cusjjs, arranged in the form of 

 the letter V. These cusps, or tubercles, thus form a triangle, with 

 the apex directed inwardly ; and this tj'pe of molar tooth, of which 

 an example is represented in the accompanying illustration, is 

 consequently known as the tritubercular. It may seem that such 

 cRowNscRFACE OF r^ point of dlstinctlou is of comparatively slight importance. Such, 



AN UPPER MOLAR , . , ^, ■ " ±^ i J- 1 



oFTHETRiTUBER- howcver, IS Dy no means the case, smce the researches or palseon- 

 coLAR TYPE. tologists have shown that nearly all the earlier Mammals had these 



tritubercular molar teeth, from which we infer that JIammals still 

 retaining them in their primitive form belong to an extremelj- ancient stock. 



From this and other structui-al peculiarities it may be taken as certain that 

 the Insectivores of the present and three following families belong to a much lower 

 type of organisation than those already mentioned. And this is bome out in a 

 remarkable manner by their geographical disti-ibution. Africa, and more especially 

 Madagascar, are charactei'ised by the number of Mammals belonging to ancient and 

 primitive types still living there, as is well exemplified by the host of lemurs 

 found in Madagascar. Now of the Insectivores with tritubercular molar teeth, 

 tlie present and largest family is restricted to Madagascar and a few of the 

 neighbouring islands ; a second is found both in Madagascar and Africa ; the third 

 is solely African : while tlie fourth is confined to the West Indies — a region also 

 peculiar for the ancient tyj)es of its few Mammals. The whole of the tenrecs, 

 which as already mentioned are confined to Madagascar and a few small islands in 

 the vicinity, are characterised by their long skulls, which are not constricted 

 between the eyes, and have no zygomatic arch below the socket for the eye to 

 connect the upper jaw with the region of tlie ear, while tlie so-called tjmipanic 

 bulla is in the form of a simple ring. 



The CoiiMON Texrec. 



Genus Centetes. 



This animal, which is the one represented in the illustration on p. 341, is 

 readily recognised by its comparatively large size, and the total absence of a tail. 

 It is the sole representative of its genus, and, from the feature last mentioned, is 

 technically known by the name of Centetes ecaudatus. Adult males attain a length 

 of upwards of IG inches, and are thus the largest of all Insectivores. The body is 



