1922] Allen, Congo Collection of Insectivora 33 



in size, dp 2 being less than half the size of dp 3 , and dp3 is less than one- 

 third the bulk of dp4. Dp 2 has a high-pointed central cusp and a small,, 

 low, sharp-pointed one before and behind it, and a cusplet on the posterior 

 cingulum. Dp 3 is similar in structure to dp 2 , but is a much larger tooth. 

 Dp 4 consists of two sections, each of which encloses a deep basin from the 

 borders of which arise four cusps, of which two are antero-external, 

 the other two internal, one of which is median and the other posterior. 

 The medio-internal cusp is usually minutely bipointed when unworn. 



The above conditions are represented, essentially or exactly, by 7 

 skulls (Nos. 49523, 49436, 49513, 49514, 49510, 49499, 49493, of Table 4). 



Permanent Dentition 



The permanent dentition comprises 36 teeth: I3E3, Cp|, P^if, M 

 |zf = ^ = 36. In this enumeration the minute upper incisor is assigned 

 as a permanent tooth, although, as already explained (p. 32), it is often 

 absent in adults, though frequently persisting through life, and has no 

 successor. The first premolar in both jaws has also no successor and is 

 developed later than the other premolars which have successors. 



Upper or Maxillary Series. — The canine is a long, slender, 

 laterally compressed, 2-rooted tooth, with a conspicuous longitudinal 

 groove on its antero-internal face. The first premolar (p l ) does not 

 pierce the gum till the milk premolars (dp 2 , dp 3 , dp 4 ) are fully developed 

 and functional, and has, as already said, no predecessor. It is a small 

 unicuspid, 2-rooted tooth, about as long antero-posteriorly as high. It 

 is separated from both the permanent canine and the permanent p 2 by 

 diastemata nearly equal in length to the basal length of the tooth. P 2 

 and p 3 are similar in form to their respective predecessors, from which 

 they differ mainly in larger size. P 4 is more completely molariform than 

 dp 4 , and differs from m 1 only in being larger and slightly more quadrate. 

 M 1 is subquadrate, the anterior half of the tooth broader than the pos- 

 terior half, with higher cusps, which are situated at the four corners of 

 the tooth. M 2 is trigonal, with three cusps, and is about one-third the 

 size of m 2 . Thus, in the permanent dentition, the last three maxillary 

 teeth are typically molariform and, on the basis of structure and posi- 

 tion, would be classified as molars, but the first one of the three has a 

 milk predecessor. 



Lower or Mandibular Series. — The three permanent incisors 

 all have bifid crowns, are close-set, directed obliquely forward, and differ 

 from their predecessors mainly in their larger size. The canine is a small 

 2-rooted tooth, separated from i 3 and pi by slight diastemata. Its axis 



