chap, ix.] TEETH : UNGULATA. 243 



A skull having left ml two-rooted, right ml being much less so. 

 C. S. M., 1059. 



338. •P- groenlandica : minute supernumerary molar on each side in 

 upper jaw making m'f . P. M., A. 2898. 



339. Zalophus californianus, an Eared Seal not far removed from 



tar la. but having p + mi instead of ~. The five back teeth are arranged 

 as a rule in a continuous series, but sometimes there is a small space 

 between the last molar and the penultimate [cp. 0. stelleri], and occa- 

 sionally they are all slightly and evenly spaced. 



One case of p + m £ on both sides and two cases of p + m£ on one 

 side only. In these the extra teeth were behind the (normally) last 

 molar and smaller than it. being without the accessory cusps seen in 

 that tooth. Allen, J. A., J\\ Amer. Pinnipeds, 1880, pp. 209, 224 and 

 226. 



340. Z. lobatus : one specimen having p + w^f on right and £ on left, 

 Leyd. M. [in addition to 3 specimens with the normal £]. 



7 — 7 



341. Callorhinus ursinus : normally £> + m£; one case having 



o — o 



and one case with - -. Allen, I. c, p. 224 (cp. No. 343). 



o — o 



deduction in numbers of molars. 



q 5 



342. Arctocephalus australis, normally p + mf : one case of „ — . 



General statement made that in cases of absence of a tooth it is the 

 antepenultimate molar which is missing [not described in a specific 

 case]. Allen, I. c, p. 224. 



343. Callorhinus ursinus, normally £; 2 cases of i. Allen, I. c. (cp. 

 No. 341). 



344. Otaria jubata, normally 4: one specimen having 4- on both sides, 

 Leyd. M.; one specimen having right 4 left 4. Leyd. M. 



Cystophora cristata: only one molar, viz. left ^ present; from the state of 

 the bones it seemed possible that the others had not been formed, but this is quite 

 uncertain. C. S. M., 1101. Macrorhinus leoninus: doubtful if the molars had 

 been present. C. S. M. 1109. 



UNGULATA. 



As to the occurrence of Variation in the dentition of Ungulates 



1 have no statistics, but a certain number of miscellaneous cases 

 have been collected from different sources. Most of the cases 

 relate to domestic animals and are given on the authority of 

 Morot and Goubaux. 



Perhaps the most interesting evidence is that regarding the 

 change of form in the "canines" of the Sheep. These teeth of 

 course have normally the shape of incisors, but in the cases 

 described by Morot they had more or less of the character of 

 canines. This evidence, though belonging properly to the Sub- 

 stantive class, is introduced here on account of its close relation to 

 some general aspects of variation in teeth. 



1G— 2 



