46 TRUNK VERTEBRA. [chap. 



in the thoracic region ; broader (in the antero-posterior 

 direction) and more upright in the lumbar region, and pre- 

 senting but scarcely any indication of that convergence 

 towards a point in the posterior thoracic region so fre- 

 quently seen in other Mammals. They are generally simple 

 and slightly dilated at their ends ; but in the lumbar region, 

 the posterior edge is often more or less bifid. 



The zygapophyses are well developed throughout. In 

 the thoracic region they are oval, flat facets, looking pretty 

 nearly directly upwards (the anterior) and downwards (the 

 posterior) : the anterior, developed on the top of the pedicle 

 and projecting forwards, being supported by the "oblique 

 process ; " the posterior is placed on the under-surface of the 

 hinder part of the lamina. In the lumbar region, their form 

 and position change, the anterior having their outer edges 

 turned upwards, and supported by a short rounded meta- 

 pophysis {mamillary process). The posterior ones have 

 undergone a corresponding change, so that their faces, instead 

 of looking downwards, are directed obliquely outwards ; they 

 are also much curved. 



The transverse processes project throughout the series 

 from the arch, near the junction of the pedicle with the 

 lamina. In the greater part of the thoracic region they are 

 tolerably long, project somewhat upwards, and slightly for- 

 wards, and are dilated and tuberous at the extremities, on 

 the under surface of which (except in the two last) they show 

 a smooth concave facet for the attachment of the tubercle of 

 the rib. In the posterior part of the thoracic region they 

 are shorter, and begin to resolve themselves into three dis- 

 tinct processes, generally conspicuous in the first lumbar. 

 One of these projects outwards, and, elongating in the second 

 and third lumbar, it forms its principal transverse process. 

 One projects upwards and forwards, by the side of the an- 



