FOSSIL AND EECENT LAGOMOEPHA. 465 



notch only by a longitudinal enamel ridge ; in the latter it is still in its place, while the 

 internal notch has grown into a transverse fold stretching across half the transverse 

 diameter of the triturating su.rface *. 



Upper Incisors of Leporidse. 



The upper incisors of several Leporida^ present some little-known peculiarities. 



In his description of Lepns nUjricollis, G. R. Wateriiouse says : — " The upper incisor 

 teeth have each two longitudinal grooves, placed very closely together, and not very 

 distinct"!. About the same statement is made with regard to Lepm yarkandensis, 

 Giinth., by Biichner, who believes this to be a special character of the species : — " Sehr 

 characteristisch fiir Lepiis yarkandensis ist der Bau der oberen Nagezahnc, durch VFclchen 

 diesc Art sich, wie es scheint, von alien Gattungsgenossen uatcrscheidet. Die 

 Vorderfiache des oberen Eackzahnes weist uamlich zwei iiache, schwach markirte 

 Binnen auf ; dieselben verlaufen dicht neben einandcr auf der inneren Halfte der 

 Vorderfiache" %. 



I have before me the type-specimen of L. yarkandensis, Guuth. (Br. Mus. Z. D. No. 75. 

 3.30.10) ; an examination of the outer surface of its upper incisors shows but one 

 groove, as in other Leporidte ; the groove is filled with cement, but only incompletely, 

 so that the outer and inner border of the zone of that substance is marked by two 

 longitudinal strisB which somewhat simulate grooves. There is besides a median 

 superficial depression of the cement layer, so that the appearance of three longitudinal 

 grooves is produced. (In Caprolagus hispidus the median hollowing of the cement is 

 more accentuated.) 



In L. niyricollis, as a rule, the appearance of two grooves is j)i*oduced by the same 

 cause as in L. yarkandensis. Sometimes, howevei", there is in the former species 

 a very sliallow longitudinal groove in the enamel, to the outside of the principal 

 groove filled with cement ; the lormer is somewhat more distinct in the unique skull 

 of a specimen from Ceylon in the Br. Mus. (Z. D. No. 81.1.29.7). 



The fact of the presence of cement in the groove having been overlooked has given 

 rise to another misunderstanding. Wuterhouse says that in Lepus ruficaudatus the 



* According to Pure Heude, the anterior upper premolar, p. 'A, of Lepus is composed of p. 3 ami a more anterior 

 premolar, which latter is said to be represented by the median of the three anterior lobes (" 6 " of my figures) of p. 3. 

 {op. cit. pp. 03, 64, pi. xiii. figs. 4, 5, 7, 189S). As I believe to have satisfactorily demonstrated — although not, 

 perhaps, to the Kev. Pore's satisfaction — that this '• 6 '" of p. 3 is tlio homologue of " (i " in the posterior premolars 

 and true molars of all Lagomorpha, I think we can, for this reason alone, dismiss the fusion theory, since each of 

 these posterior teeth woidd have to be considered also as a compound of two. (Similar remarks apply to p. 2 of the 

 lower jaw of Lepus, which, according to Pere Heude, is = p. 2 + p. 3.) I may add here that I have never observed 

 in the upper molars or premolars oi Lepus a longitudinal enamel ridge closing the opening of the internal enamel- 

 inflection (rt of my figures), as figured and described by Pere Heude ("fissure qui se ferme avec unc lamellc d'email 

 chez I'adulte," op. cit. p. 65, pi. siii. fig. 4), and would gladly learn in which species this occurs. 



t G. li. Waterhouse, ' A Natural History of the Mammalia,' ii. p. 73 (1S4S). 



j Eug. Biichner, ' Wiss. Eesultate der von X. 31. Przcwalski nach Central-Asien unternommenen Keisen,' i. 5. 

 p. 193 (1894). 



SECOND SERIES. — ZOOLOGY, VOL. VII. 05 



