1892.] POSITION OF NOTORYCTES TYPHLOPS. 367 



Pm. 1 is canine-shaped, projecting above the incisors and the 

 canine; it is present in both sides in males I., II., V., females III., 

 IV., and specimen C. 



Pm. 1 is very much reduced to a short pointed weak tooth in the 

 right side of specimen B and female I., in both sides of specimen A. 

 Pm. 1 is absent in the left mandible of specimen B, 

 The canine tooth, i. e. the fourth in the series, fitting upon the 

 fourth upper tooth, which latter is implanted immediately behind 

 the premaxillary suture, is generally weaker than the incisors, never 

 projects above the series, and shows occasionally a slightly uneven 

 crown. The lower canine is thus fully developed in the right side 

 in males I. and II., female I., and in specimens A, B, and C. 



The canine is reduced to a very small pointed tooth on the left 

 side in males I., II., V., and in female I. 



The canine is reduced on both sides in female III. 

 The canine is absent on the left side in female IV., in specimens 

 A, B, and probably in C. 



Concerning the incisors, they diminish in size from the first to the 

 third. In most specimens three incisors are present in both man- 

 dibles, but in the left of female IV. and of specimen C there are 

 only two incisors, which in female IV. are followed by a gap in front 

 of the first premolar, and in specimen C by a smaller gap in front 

 of the reduced canine. 



Comparison of these nine apparently adult specimens shows the 

 tendency of reduction of the left lower canine and of either pm. 1 or 

 pm 3. The reduction, resulting often in ultimate loss, seems quite 

 irregular, there being apparently no compensation effected by the 

 size of the neighbouring persisting teeth. 



The most remarkable feature is, however, that the reduction 

 either in numbers alone, or in size, or in both is undoubtedly greater 

 in the left mandible than in the right. This fact seems well 

 established, considering that out of the nine specimens examined 

 the left-sided reduction is greater in not less than eight specimens ; 

 reduction in size alone in three, in numbers in five specimens. 



The total number of teeth in the nine right mandibles is 86, in the 

 corresponding left mandibles only 79. The number of reduced and 

 of absent teeth on the right side is 11, on the left side 19. Such a 

 decided asymmetry is practically unique ; I have failed to perceive 

 any corresponding asymmetry in the size of the two mandibles. 



The teeth in the upper jaw are much more regular. Three 

 incisors are followed by an equally small canine. The first of the 

 premolars is small, the second large. The four molars are always 

 present and do not vary in size. 



In specimen C the right and left upper sides possess each only 9 

 teeth, the third right incisor has been lost and has left a gap, while 

 on the left side the canine seems to be absent without a distinct gap. 

 In female IV. left side, and in female I. right side, there are like- 

 wise only 9 teeth ; the four molars are complete and so are the two 

 premolars, while the canines seem to be absent, with perhaps a 



slight gap. 



26* 



