* 



244 MERISTIC VARIATION. [part i. 



It is noticeable that there is so far no case of an incisor appear- 

 ing in the upper jaw of Ruminants. 



The evidence is divided into two groups, the first relating to 

 incisors and canines, the second to premolars and molars. 



Incisors and Canines. 



345. Elephas africanus </ : the left tusk imperfectly doubled. The 

 root of this tooth was double 1 , one root being outer and the other inner. 

 The half of the tusk arising from the outer root twisted round and over 

 the other half so that at the other end it lay above and internal to it. 

 The structure of the tusk was essentially double, but the two parts 

 were more or less blended together in the middle third. The ex- 

 ternal ends were separate, but broken and somewhat deformed. 

 Friedlowsky, A., Sitzuugsb. d. K. Ak. Wien, 1868, lix. i. p. 333. 

 Plate. 



346. Horse. Supernumerary incisors common. Magitot, Anom. Syst. 

 dent., p. 104, Plates. Numex'ous specimens in Museum of Veterinary 

 School at Alfort. 



347. Specimen having 1 2 upper incisors and 1 2 lower incisors belonging 

 to the permanent dentition. Goubaux, Kec. med. vet., 1854, Ser. 4, i. p. 

 71. Similar observation, Lafosse, Cours Hippiatrique, 1772, p. 32. 



348. Extra teeth of more or less irregular form placed behind upper 

 incisors very common : many specimens in museum at Alfort. Speci- 

 men having left f as a double structure, the two halves not being 

 separated. (Alfort Mus.) Magitot, I. c, PI. xix. fig. 25. 



Absence of incisor in Horse is rare. Goubaux, who has largely studied the subject, 

 knew no case of absence of any tooth in Horse, /. c. 



349. Skeleton of Cart-mare in C. M. has only two incisors on the left side in the 

 upper jaw. The teeth stand evenly and without break or trace of auy other incisor 

 having been present. There is no sufficient indication to shew which of the incisors 

 is missing, but the two incisors present agree most nearly with i- and i 3 . This 

 specimen was first pointed out to me by Mr S. F. Harmer. (See also case given by 

 Rudolphi, Anat.-phys. Abh., 1802, p. 145.) 



*350. Mare of common breed, foaled March, 1876, having in the upper jaw no i s in 

 either milk or permanent dentition, and in the lower jaw no permanent i 3 . In the 

 upper jaw there were only 4 milk incisors, which were subsequently replaced by 

 4 permanent incisors. Animal seen by Mokot in Apr. 1880; it then had 4 per- 

 manent incisors in the upper jaw, but no i 3 . In the lower jaw permanent i 1 and i a 

 were in place, together with i 3 of the milk series on each side. As Morot remarks it 

 is still possible that the other incisors might appear. Dam normal ; half-sister 

 abnormal, given in next case. Morot, Bull. Soc. mid. vet., 1885, Ser. 7, n. p. 125. 



*351. Mare out of same mother as last case, by another sire, foaled Apr. 1877, had only 

 4 milk-incisors in upper jaw. Seen by Morot at 3 years old, had then the teeth of 

 lower jaw normal, viz. permanent i 1 , and milk ;' 2 and i 3 all in place. In upper jaw 

 were permanent i l and milk i" on each side. The right milk i- on the external side 

 had a light groove parallel to the long axis of the tooth, suggesting that it might be a 

 double structure, but the groove was very slight and the crown was single. At five 

 years old this animal had the normal 6 lower incisors, but in the upper jaw left i 3 

 was absent. On the other hand a well-formed supernumerary tooth stood behind 

 right i 3 , right i- being partly rotated. Ibid., p. 127. 



1 See also a curious case of " nine tusks " imperfectly described by Chapman, J., 

 Travels in Interior of S. Africa, n. p. 98. 



