150 



Front view of laniary 

 incisors, magn., Urotri- 

 chus tdlp&ides, Temminck. 



Fie. 3. 



Side view of upper laniary and 

 mandibular dentition, Potamogale 

 velox, nat. size (ex Allman, loc. cit.). 



the homologue of the laniariform i i in Potamogale ; but the pair of developed inci- 

 sors in Urotrichus arc what Dr. Falconer would have described 

 as " approximated and placed collaterally, as in the placental 

 Rodents"* ; i. c. they are in contact, side by side (Cut, fig. 2). 

 In the large African' Ferine (Carnassier, Cut.), with the habits 

 and food of the Otter, discovered and called Potamogale by Du 

 Ciiaillu, the first incisor of the upper jaw (fig. 3, i i) "closely 

 resembles a large projecting canine"f. In the lower jaw "the 

 first is very small. The second incisor is high, conical, curved ; 

 it is sharp-pointed, and resembles a canine" %. "The condyle 

 is borne on a distinct neck"§. The low position of the condyle 

 (b), associated with these laniariform incisors in Potamogale 

 (fig. 3), is not alluded to either by Allman (/. c. p. 11) or by Mivart (I. c. p. 127) 

 It is important in association with the position and jux- 

 taposition of the laniaries in this large fish-hunting 

 Ferine, with regard to the moot question of the car- 

 nivority of Thylacoleo and Plagiaulax. 



In Myogale, as in Solenodon, the first upper incisor 

 " is much larger and more vertically extended than in 

 any other tooth in the skull. Its crown is triangular, 

 it is in contact with its fellow of the opposite side, and predominates more than does 

 any other form yet reviewed, except, perhaps, that of Sorex. It is opposed mainly to 



the second incisor of the lower jaw, the first being much smaller This second 



incisor is exceedingly large, pointed and conical" ||. "The canine is a small obtusely 

 pointed- toothy," as in Thylacoleo. In Solenodon, Potamogale, and Myogale the laniari- 

 form incisors of the lower jaw, to which those in Urotrichus and Sorex may be homo- 

 logous, are divided from each other, at their base, by a very small pair of anterior inci- 

 sors ; but the extent of separation is slight, and cannot affect in any appreciable degree 

 their piercing power. 



Indeed, to concentrate is to give force, to divide is to weaken. If it be not carried too 

 far, divarication may aid in the secondary work of holding the pierced prey : but for 

 the primary lethal operation, the base for the grasp of the biting muscles is as broad in 

 Thylacoleo as in Pel is. An estimate of the concentrated force of these enormous muscles 

 upon the pair of lower laniaries approximated as one piercing, lacerating organ, with the 



* X. p. 352 ; XI. p. 435. 



t Allman, " On the Characters and Affinities of Potamogale," Trans. Zool. Hoc. vol. vi. (1866) p. 6. I am 

 indebted to the accomplished author of the above-cited interesting Monograph for the drawing which is the 

 subject of the Cut, figure 1. + lb. p. 7. 



§ lb. p. 11. (Compare this " pedunculate" character with that in Plagiaulax, figure 10.) 



|| Mivaut, op. cit. Journal of Anatomy and Physiology, vol. ii. p. 124. 



•j" Id. ib. p. 125. " Scalops. The first incisor is very large, and is opposed to one nearly as long in the 

 Lower jaw, where the canine is wanting, or represented by a most minute and rudimentary tooth." — Ib. 



