FOSSIL AND EECENT LAGOMOEPHA. 487 



{PL 39) represents these parts of a young SylvUagiis braslliensis (Linn.), wliich closely 

 resembles Faheolagus in the great antero-posterior extension of both the palatine and 

 the maxillary bones and in the very narrow palatal notch, both coming near to the 

 normal condition of Mammals. 



As might have been expected, the Pliocene Lepus valdarmnsis, Weith., also presents a 

 more normal palatal region than the various specialized species of Lepus, and may for 

 this reason alone be assigned to the Caprolagus section. The anterior and posterior 

 palatal notches are much narrower than in L. europcvus, and the whole of the bony 

 palatal In-idge is considerably longer ; this being especially due to the elongation of the 

 maxillaries *. 



The greater rednction of the palatal plate of the maxillary bone in Lagomyidfe, 

 as compared with Leporidge, might seem to be due to the greater backward prolongation 

 of the foramina iucisiva in the first-named family. On closer examination, however, 

 it becomes evident that in reality we have to do with a fusion of two originally separated 

 vacuities, viz. the true foramina incisiva, and a sort of palatal fontanelle behind them. 

 In Lagomys, the premaxillse generally, though not in all the species, join in the middle 

 line between the foramina incisiva and the fontanelle behind them ; in Leporidte, the 

 confluence of the two fissnres has generally, but not always, become complete. An 

 approach to Lagomyidse (fig. -30) is given by the bottle-shaped appearance of the 

 "foramina incisiva" which Bangs considers to be characteristic of ''Lepus sylraticus 

 transitionaUs "f — the same occurs also in other American Leporidfe — ^and which is but 

 the remnant of the original separation of the true foramina incisiva from the palatal 

 fontanelle. I therefore do not think that Winge is right, when he assumes that the 

 separation of the two openings is a secondary character in Lagomys, brought about 

 by the new formation of a bony plate $. Judging from Cope's figure §, the fusion of 

 botb openings seems to have already taken place in PalcBolagus. But if we judge from 

 recent forms, in which tlie premaxillai are very thin in this region, it ajipears probable 

 that the apparent fusion in the figured palate of Palceolagus is due to the defective 

 preservation of the premaxillas in the figured specimen. 



On the Limb-Skeleton of Lagomorpha. 



There is a great diff"erence between the Lagomyidte and Leporidfe, and between the 

 various members of the latter, in the absolute length of the fore and hind limbs, and in 

 theii- relative length, compared with each other. The diff'erences, moreover, are not only 

 in size ; and it is the antebrachium which in the first place presents notable divergences 

 in the different groups. Even for systematic purposes it will be necessary henceforth to 

 take into consideration these, as well as other, parts of the skeleton ; and we cannot 

 content om-selves with such general statements as " hind limbs longer than the fore 

 limbs," and " hind Umljs and fore limbs subequal." 



* A. Weithofer, in Jahrb. k.-k. geol. Keichsaustalt, Bd. xxxix. p. 80 (1880). 

 t Proc. Bost. Soc. Nat. Hist. ssvi. p. 407 (189.5). 



X H. AVinge, ' Jordfundne og milevende Gnavere,' &c., J. c. p. 113 : " Forskjelleii fra Haren er kuo, at det ogeulige 

 F. incisivum er afskilt ved en nyopstaaet, ikke altid fukUtii'ndig Benbro."' § O^j. cit. pi. Isvi. fi"-. 1. 



