30 PROFESSOR OWEN ON THE CHARACTERS, ETC. 



interval. The true molars -have their grinding surface marked by 

 two double crescents, the convexity of which is turned inwards in 

 the upper and outwards in the under jaw. 



Many fossil Artiodactyles, with similar molars, appear to have 

 differed from the Ruminants chiefly by retaining structures which 

 are transitory and embryonic in most existing E-uminants, as, e, g. 

 upper incisors and canines*, first premolars, and separate meta- 

 carpal and metatarsal bones ; these are among the lost links that 

 once connected more intimately the Ruminants with the Hog and 

 Hippopotamus. 



The Pachyderms in the Cuvierian system included all the non- 

 ruminant hoofed beasts ; they were divided by the great French 

 anatomist into the JProhoscidia, Solidungula, and Pachydermata 

 ordinaria, the latter again being subdivided according to the odd 

 or even number of the hoofs. I have on another occasion f adduced 

 evidence to show that the right progression of the affinities of the 

 Ungulata was broken by the interposition of the Horse and other 

 Perissodactyles between the non^ruminant or omnivorous and ru- 

 minant Artiodactyles ; and that too high a value had been assigned 

 to the Ruminantia by making them equivalent to all the other 

 Ungulates collectively J. 



* In a new-bom Dromedary (Camelus Dromedarius, L.), whicli perished in 

 the birth at the London Zoological Gardens, the following was the state of the 

 dentition. In the upper jaw there were six deciduous incisors (3 — 3), which 

 were calcified, and presented a larger proportional size than any rudiments of 

 those teeth that have been noticed in ordinary Ruminants, and they leave con- 

 spicuous alveoH in the premaxillaries : the deciduous canine and first functional 

 milk-molar (d. 2) were small, the latter with a simple crown ; the second {d. 3) 

 and third (d. 4) molars were large, bilobed, and each lobe was bicrescentic. * In 

 the lower jaw the six incisors and two canines form a semicircular series of 

 nearly equal teeth, with overlapping leaf- shaped crowns, the deciduous canines 

 more resembling the incisors than the permanent ones do : the functional 

 molars are but two in number, on each side ; the first is small, simple, conical, 

 compressed, notched behind ; the second is very large and three-lobed, each 

 lobe being bicrescentic, and the last the largest. Only the summits of the cres- 

 cents of the molar teeth had pierced the gum (Catal. of Osteology, Mus. Roy. 

 Coll. of Surgeons, vol. ii. p. 577, 4to, 1853). 



t Quarterly Journal of the G-eological Society, December 1847. 



X Since the communication of my paper on the classification and affinities of 

 the hoofed animals to the Greological Society, Nov. 3, 1847, in which the 

 grounds for the division of the Ungulata into two orders, according to the 

 parity or imparity of the digits, as proposed in my ' Odontography,' are given 

 in detail, the idea has been ventilated and more or less adopted by M. Pomel 

 (Comptes Rendus de I'Acad. des Sciences, June 19, 1848), and by M. Gervais 

 (Zoologie et Paleontologie Fran^aise, p. 42). The latter experienced palseonto- 

 logist, extending the term * Pachydermes ' to include all the Ungulates, divides 



