Proceedings of the Scientific Meetings of the Zoological Society of London 1870

Page 543

18/0.] DR. J. MURIE ON SAIGA TARTARICA. 453 vertebral foramina pierce the sides of the body almost vertically, close behind the root of the cranial articulating processes. The postarticular surface of the body is tolerably level and semilunar. A short knobby sessile projection represents the ventral keel (hypa­pophysis); it is situated far back. As regards the antero-posterior diameters of the bodies of the cervicals, the following numbers express a sufficiently near approxima­tion to their relative sizes in inches and decimals:-1st, 1*2; 2nd, 2*3; 3rd, 1*6; 4th, 1*6; 5th, 1*5; 6th, 1*3; 7th, 1*0. By such it is seen that the axis is the longest of the neck-vertebrae, as, indeed, obtains in many of the Ruminantia, although in the long-necked Giraffe and Camelidae, where the whole of the cervicals are subequally long, it is not so obvious. Its neural spine is also by far the strongest, an inch high, and two antero-posteriorly; thick and stout, with an expanded, roughened, free border, cleft behind (hyperapophyses of Mivart * ) , but single and produced in front, where it overlies the posterior incised portion of the laminar arch of the atlas. The wide foramen for the vertebral artery enters the spinal canal at the anterior end and upper lateral surface of the body. The odontoid process is short, gouge-shaped, and surrounded by a wide, flattened, semilunar articular surface. The transverse processes are of considerable size, though nevertheless small, as com­pared with the great wing-like processes of the atlas. Moreover they disagree with these latter in being concave below and more convex above, and in their derivative angle from the body being more acutely backwards. There is only a rudiment of a pleurapo-physis at the root of the diapophysis. A deepish ventral spine exists for nearly the whole length of the body. Posteriorly it is bulbous, but in front of this thin, sharp, and laterally compressed. The third and fourth vertebrae present characters very much akin to each other. They agree in the great reduction of the spine, deeply bifid in both, smallest in the third, but in each only occu­pying the anterior half of the neural arch-in the great lateral ex­pansion, flattening, or even forward concavity of the neural laminae- in the broadening and more outstanding position of the transverse processes-in possessing large diapophyses-in the production of the keel being slightly less than in the axis, and more concavely marginate. The distinctive differences are:-in the fourth having the highest spine; but the third, while less high, has the neural laminae pro­duced forwards as a low process, which fits into the triangular in­terspace between the posterior articulating (or zygapophysial) facets of the axis; in the laminar arch of the third being slightly broader and less concavely marginal; in there being only an obscure metapo­physis in the third, whereas it is fairly developed in the fourth ; in the transverse process and diapophysis of the third running antero-pos­teriorly almost in the same plane, whilst in the fourth they are at a distinctly obtuse angle to each other. The alteration of the configuration of the fifth cervical consists in * " Axial Skeleton in the Primates," P. Z. S. 1865, p. 576.