THE YERTEBEAL COLUMN. 



17 



the eig'htli, presents an articular head covered with cartilage ; the 

 anterior surfaces, with the exception of the ninth, present corre- 

 sponding articular depressions, covered with cartilage. 



b. The arclies, which have some- ^'S- 4- 



what sharp margins both before and vivT^ii 



behind, bear the following pro- 

 cesses : — 



1. The articular processes (Figs. 

 4 and ^ oo) are similarly placed 

 to those of the dorsal vertebrae of 

 man: they project horizontally, the 

 cartilaginous articular surfaces on 

 the posterior processes being directed 

 downwards, those on the anterior 

 upwards. 



2. The transverse processes 

 (Figs. 4 and 5 t t') are strong. Hat, 

 and of very varying size and direction . 

 The transverse processes of the fourth 

 vertebra are the longest, those of the 

 third only a little shorter; the shortest 

 are those of the seventh and eighth. 

 The atlas has no transverse pro- 

 cesses. Those of the second and third 

 vertebrae project directly outwards 

 and slightly downwards; those of 

 the fourth, fifth, and sixth upwards 

 and backwards. The seventh and 

 eighth project more dii'eetly outwards 

 and at the same time backwards ; 

 the ninth upwards and markedly 

 backwards. All the transverse pro- 

 cesses have cartilaginous epiphyses ; 

 the largest are those of the second, 

 third, fourth, and ninth vertebrae. 



3. The spinous processes are 

 generally small, but individually of 

 varying size, appearance, and direc- 

 tion. The longest are those of the third, fourth, and fifth vertebrae ; 

 these are, in transverse section, of a thi'ee-sided prismatic form, as 



c 



Vertebrae of Rana esciiloitci, seen from 

 below, twice the natural size. 

 I to g First to ninth verte brse. 

 c Urostyle. 

 o Articular processes. 

 sc Tlie two facets for articulation with the 

 urostyle. 



