114 INSECTIVOEA. 



notch between the two being of considerable depth. From the condyle there is 

 a nearly vertical line to the posterior process of the angle of the jaw, which is a 

 strong hook curved downwards, upwards and inwards, with a central ridge on 

 its inner aspect with a groove above and below it. The dental canal commences 

 below and slightly anterior to the condyle, and opens externally below the first 

 premolar. 



The replacement of the deciduous by the permanent teeth I have been able 

 to trace in three specimens, one of which is remarkable from the cu'cumstance that 

 it presents eleven teeth on one side of the upper jaw and ten on the opposite side — an 

 abnormality full of interest. 



The first skull has all its deciduous teeth intact, except one, and yet, contrary 

 to what prevails among Insectivora generally in which the deciduous teeth are 

 shed at an early period, it is nearly the size of a full-grown cranium, and the indi- 

 vidual as a mounted specimen has all the appearance of full age. From these skulls 

 it would appear that Horsfield's representations of the dentition of T. ferrwginea 

 and T. javanica exhibit deciduous dentition, and that Miiller and Schlegel's figure 8, 

 plate 27, does the same. Professor Mivart has fully described the characters of the 

 grinding surface of the molars, and pointed out, what these specimens fully verify, 

 that the third deciduous premolar resembles the true molars, but is replaced by a 

 tooth of a markedly different character. 



I shall describe the deciduous teeth, and indicate in j)assing in what respects the 

 permanent teeth differ from them. 



Commencing with the third premolar, that tooth has three external small cusps 

 on a Hue, and resembles a molar, the central cusp showing indications of a minute 

 cusp at its hinder extremity, two median pointed cusps, and a large internal cusp 

 almost embracing the other two with a small supplementary cusp at its base on its 

 posterior surface. The two external fangs are long and fine, and spring from the two 

 internal cusps ; the inner fang is stronger and stouter than the other. The long 

 central cusp of the permanent premolar is wedged in between the two long external 

 fangs of the deciduous tooth, and by the pressure on the tooth push it outwards, even 

 causing it to decay. 



The second premolar consists of a long laniar-Hke central cusp with an 

 internal and a postero-external cusp, the last connected to the large cusp by a weU- 

 marked ridge. The large cusp corresponds to the long median cusp of the third 

 deciduous premolar and to the median cusp of a molar. It is flattened on its inner 

 aspect, and at its base it has the projecting ridge or inner cusp of the faintly 

 developed cingulum. Tliis cusp and the two others are fastened in the jaw by a 

 corresponding number of long fangs, the two outer of which are divergent. 



The first premolar has two cusps ; the large anterior cusp partakes more of the 

 character of the head of the canine than of the large cusp of the other premolars, 

 and has a small posterior prolongation not nearly so high as itself, sloping off to the 

 gum ; each cusp is supported by a long and strong fang. There is no internal cusp. 

 This deciduous tooth is the first to fall out. 



