420 INSECTIVORES. 



I 



subquadrate four-pointed crowns above : below they are narrower, 

 and the anterior and inner angle is produced into a fifth cusp. 



The true molars of the tropical Hedgehogs, forming the subgenera 

 Echinops and Ericulus, are more simple, and approach the form of 

 those in the Chrysochlore, being compressed from before backwards, 

 with two outer cusps and one inner cusp in the upper jaw, and with 

 one outer and two inner cusps in the lower jaw. The number of 

 incisors is |e| in both subgenera, which are followed by |£| small and 

 simple premolars ; but Ericulus{l) has g compressed tri-cuspid 

 molars, and Echinops only |eJ(2). 



The largest species of the present family, called Tenrecs(3) or 

 tail-less Hedgehogs of Madagascar, combine the simple molars of the 

 Ericulus with the most formidably developed canines which are to 

 be met with in the whole order Insect Ivora. The incisors are two 

 in number in the upper jaw and three in the lower jaw ; very small 

 and sub-equal in both : the canines are long and large, compressed, 

 trenchant, sharp-pointed, recurved, and single fanged; thus presenting 

 all the typical characters of those teeth in the Carnivora ; they are 

 separated, in both jaws, by a wide space from the premolars : the 

 first premolar above is compressed, unicuspid, with a hinder talon, and 

 two-fanged ; the second has a larger prismatic tricuspid crown, and 

 three fangs : of the four posterior teeth, wdiich by their antero- 

 posterior compression may be regarded as true molars, the first 

 three have tricuspid crowns as in the Echinops, and have three 

 fangs ; the fourth is smaller, is bicuspid, and has two fangs : all the 

 lower molars have two fangs. The Tenrecs prey more upon serpents 

 and lizards than on insects, and thus approximate the true Carnivora 

 in diet as well as dentition. 



164. Structure and Succession. — The teeth of the Insectivora consist 

 of a basis of hard dentine with a thick coronal investment of enamel, 

 and an outer covering of cement. This third substance is very 

 recognizable in the interspaces of the coronal cusps in microscopic 

 sections of the molars of the larger species, as the Tenrecs and 

 Macroscelles ; and is always thick where it closes the extremity of 



(1) PI 111, fig. 6. 



(2) See Mr. Martin's Memoir in the Zoological Transactions, vol. ii, p. 249. 



(3) PI. 110, fig. 6. 



