896 



SIR V. BROOKE ON THE 



[Nov. 19, 



Facts (continued). 



(8) In some of the Telemeta- 

 carpi the distal extremities of 

 the lateral metacarpals is two 

 thirds the length of the meta- 

 carpal cannon. In some of the 

 Bovidae (e. g. Gazelld), of which 

 family all the species are plesio- 

 metacarpal, the proximal extre- 

 mity of these bones is two thirds 

 the length of the metacarpal 

 cannon. 



(9) With three exceptions all 

 the Old-world Deer are plesio- 

 metacarpal ; and with one excep- 

 tion all the New-world Deer are 

 telemetacarpal. 



(10) In none of the Old- 

 world Deer is the vomer suffi- 

 ciently prolonged backwards to 

 divide the nasal cavity into two 

 chambers. In all the New- 

 world Deer the nasal cavity is 

 so divided. 



(11) The vomer of Megaceros 

 hibernicus exhibits an interme- 

 diate condition. The limb in 

 this form is plesiometacarpal, 

 and as highly specialized as in 

 the existing Plesiometacarpi. 



(12) The Telemetacarpi of 

 the Old World resemble the 

 Plesiometacarpi in the form of 

 their vomer and in the position 

 of the metatarsal tufts. 



(13) Thirty-three out of the 

 thirty-nine species of Old-world 

 Deer are inhabitants of the In- 

 dian or East Palsearctic regions ; 

 and of the eleven subgenera into 

 which they are divisible there is 

 only one (Dama) that has no 

 representative in these regions. 



Hypothesis (continued), 

 tacarpal and telemetacarpal con- 

 dition of limbs in existing Cer- 

 vidae. (9) It is probable that 

 the separation between the upper 

 and lower extremities of the me- 

 tacarpals took place long after 

 the first Dremotherium-Mke Cer- 

 vidse had found their way into 

 North America. In these the 

 default in ossification began in 

 the upper third of the lateral 

 metacarpals; (12) whilst in the 

 Cervidae remaining in the Old 

 World both modes of reduction 

 obtained a footing, the Plesiome- 

 tacarpi gaining ultimately the 

 preeminence. (10) The vomer 

 in the early forms of Deer was, 

 as in the existing less-specialized 

 Artiodactyles (e. g. Hippopota- 

 mus, Sits, Tragulus), prolonged 

 backwards, dividing the nasal 

 cavity into two distinct chambers. 

 (11) As the competition be- 

 tween rapidly multiplying and 

 allied forms became severe in the 

 Old World, specialization exten- 

 ded to this part of the cranium, 

 and a reduction in the backward 

 extension of the vertical plate 

 of the vomer, and consequent 

 modification of the surrounding 

 parts, set in. It is not impro- 

 bable that the limbs of the Plesio- 

 metacarpi had nearly reached 

 their present stage of specializa- 

 tion before the form of their 

 vomer departed from the primi- 

 tive type. The Deer of the 

 New World, being less numerous 

 both in individuals and species, 

 and not being subjected to such 

 severe competitions as the Old- 

 world Deer, retained the primi- 

 tive form of vomer. The greater 

 development of the antlers in the 

 larger majority of Old-world 

 Deer, as compared with those 

 of the New -world Deer, may be 



