CHAP, in.] SKELETON OF THE HEAD AND TRUNK. 39 



upwards and outwards, outside the prezygapophysis, is termed the 

 mammillary process, or Metapophysis. 



The posterior process ((7,), which projects backwards as much as 

 any other part of the vertebra, is called the accessory process, or 

 Anapophysis. 



The prezygapophyses look almost entirely inwards, while the 

 postzygapophyses (5) look almost entirely outwards. 



The twelfth and thirteenth dorsal vertebra) are like the eleventh, 

 but their anapophyses are stouter and their neural spines are larger 

 and project more forward. 



7. The seven LUMBAR VERTEBRJE are larger and more massive 

 than the dorsal vertebrae, and increase in size as we proceed back- 

 wards as far as the sixth lumbar (see Fig. 23). 



Selecting the fifth for comparison with the fifth dorsal, we find its 

 centrum broader in proportion to its depth, about twice as long, 

 less convex transversely below, and 

 with a slight median ridge, called 

 hypapophysial* running from before 

 backwards, along its under surface. 

 The neural lamina and pedicel are 

 much longer, and the latter, though 

 deeply notched behind, is scarcely at 

 all so in front. 



The neural spine is very much 



i , -, i , -i -n iJ'i Fig. 17. SIDE VIEW OF THE 



Shorter, absolutely aS Well aS relatively. TENTH AND ELEVENTH VERTEBRA, 



It is elongated from before backwards, ""^JS^Wta 

 and inclines forwards instead of back- 11! Eleventh vertebra. 



wards, thus agreeing with the last J ffiS process. 



three dorsal vertebra*. * %%%*** 



The zygapopnyses are tmcker, ana which conceals from view 



their articular surfaces are differently Pt c^SSwSS*' 



shaped from those of the dorsal vertebrap. * SSo? P Z y|apo P h y sis. 



Each prezygapophysial surface is 5. Posterior zygapoptiysis. 



concave, and looks inwards as well as 



upwards. The postzygapophysial surfaces are convex, and look 

 outwards as well as downwards, being embraced by the pre- 

 zygapophyses of the vertebra next behind. The transverse processes 

 are very much longer than those of the dorsal vertebra), and project 

 very much forwards and strongly downwards as well as slightly 

 outwards. There are no capitular or tubercular surfaces, the 

 lumbar vertebrae not bearing ribs. 



The metapophyses and anapophyses are large and conspicuous, 

 though not more so than in the last dorsal vertebra. 



The neural canal is larger and more quadrangular than in the 

 dorsal region. 



The more anterior lumbar vertebra) closely resemble the mor 



* Because it represents a certain process, present in many other animals, 

 which is called a hypapophysis. 



