MAMMALIAN ORDERS. 



285 



Perissoclactyles, represented by the existing genera Rhinoceros, 

 Hyrax, Tapir us, and Equus. 



In the even-toed or * artiodactyle ' Ungulates, the dorso-lumbar 

 vertebrae are the same in number, as a general rule, in all the 

 species, being nineteen, fig. 166, d, l. The vertebral formulae of 

 the Artiodactyle skeletons show that the difference in the number 

 of the so-called dorsal and lumbar vertebra? does not affect the 



166 



Artiii(l;ictylc skeleton i^Ccrvus ^[cgacr,|■os^. xviir 



number of the entire dorso-lumbar series : thus, the Indian Wild 

 Boar has d. 13, Z. 6 = 19; the Domestic Hog and the Peccai-i 

 have d. 14,1 5 = 19; the Hippopotamus has d. 15, /. 4 = 19 ; the 

 Gnu and Aurochs have d. 14, /. 5 = 19 ; the Ox and most of tlie 

 true Euminants have d 13, Z. 6 = 19; the aberrant Ruminants 

 have c?. 12, /. 7 = 19. The natural character and affinities of the 

 Artiodactyle group are further illustrated by the absence of the 

 third trochanter in the femur, ib. 65, and by the place of perfora- 



