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Show 1892.] POSITION O F N O T O R Y C T E S T Y P H L O P S . 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 mandibles, 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 frout 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 likewise 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. fi# |
