242 



Scientific Proceedings, Royal Dublin Society. 



shows the additional fold, whilst in the right p. 3 " « " is obsolete. 

 Fourteen of the Scotch skulls in the British Museum have the p. 3 on 

 either side typical. The remaining eight show reductions on the inner 

 side of the p. 3. In some of these the inner fold " a " is simply shallow, 

 or the cusp " 8 " somewhat reduced — the condition of this tooth in the fossil 

 skull in Mr. Lewis Abbott's collection — but in others it appears to be absent ; 

 the third fold seen in these latter cases being, in my opinion, the little extra 

 fold cutting the antero-internal cusp " 8 " of the complicated teeth mentioned 

 above (e.g., St. Mary's Loch, Selkirk, 0.2. 24.2; Cawdor Nairn, ? 98.11. 21. 2 ; 

 Cromlix Dunblane, (? 97. 5. 13. 1). It is thus evident that the additional fold 

 in question frequently occurs in L. var. scoticiis. On the other hand, I have 

 not succeeded in finding it in any of the numerous skulls of L. var. hibernicus 

 before me. 



Antekiok Upper Premolars 

 of type skull of L. variabilis anglicus, seen from below. 

 A = right p. 3 ; B = left p. 3 (enlarged). 



This extra fold does not appear to have been previously noticed ; but 

 indications' of it are seen in the following figures given by Forsyth Major" 

 Lepm mgricollis, p. 3 (fig. 34) ; Prolagus sardus, p. 3 (fig. 24) ; Prolagus 

 ceningensis, p- 2 (fig. 10), Titanomys fontanesui? p. 2 (fig. 9), and Titanomijs 

 msenoviensis, p. 2 (fig. 19) in the latter being especially well marked. If I am 

 right in regarding this extra fold of the p. 3 as homologous with that seen in 

 the Titanomys tooth, then we may regard it as a very primitive feature in the 

 dentition of the Hare, which has survived to some extent in the Scotch form, 

 and which was occasionally present in the Pleistocene form of L. variabilis of 

 the south of England. Elsewhere it appears to have totally disappeared 

 in the variabilis group. 



' Forsyth Major, 

 vol. vii., pi. 36. 



' On Fossil and Recent Lagomorpha," Trans. Linn. Soc, ser. ii., Zool., 



