— 122 — 



The bodies of the lumbar vertebrae are colossal and even increase in bulk 

 somewhat to the rear. The osseous epiphyses are here generally more firmly 

 united with the centrum than in the dorsal region, though there are a few 

 that are not quite incorporated, but fit against the centrum of the vertebra 

 by means of a granulated surface. 



The neural-foramen diminishes towards the rear. The spinous processes 

 are mostly somewhat longer than in the dorsal vertebrae but towards the 

 rear end they again diminish in length. The transverse processes are conspi- 

 cuously flat, those of the 1st lumbar vertebra only having retained some of the 

 knobby expansion occuring in the dorsal vertebrae. Towards the rear those 

 processes at first increase slightly in size, so as to reach a length somewhat 

 superior to those of the dorsal vertebrae. Further to the rear however they 

 become much shorter untill for the hindmost lumbar vertebrae they are 

 shortened by nearly one half. 



The anterior articular processes serving similarly to those in the last 

 vertebrae thoracis exclusively for the attachment of tendons belonging to the 

 interior fascicles of the longissimus dorsi, have the peculiar square appearance 

 brought out in the illustration and become a little smaller only quite at the back. 



The vertebrae caudales (fig. 26 — 32) are in other Vertebrata posterior to 

 the sacrum. It being however impossible to speak of a sacrum in Cetacea, 

 the criterion to mark the beginning of the caudal series must be the first 

 attachment under a vertebra of a chevron-bone formed by the haemapophyses. 



According to this criterion there are 27 caudal vertebrae bringing the total 

 number of vertebrae to 65, a maximum for various species of Balaenopteridae. 

 A type of the caudal vertebra proper is not to be indicated, seeing that the 

 anterior ones are quite similar in shape to the latter lumbar vertebrae, whereas 

 the various processes become gradually smaller towards the rear, pass to 

 rudimentary conditions and finally vanish altogether, so that the last nine 

 or ten vertebrae caudales present no more processes whatever. The bodies of the 

 vertebrae caudales at first diminish very slowly in volume, and it is only with 

 the 12th that a rapied diminution of the bulk sets in. The foramina of the ver- 

 tebrae however diminish rapidly in width of the bore and even disapper al- 

 together, as is visible in the illustration (see below). 



The spinous process, which in the first few vertebrae caudales still bears 

 the character of those in the lumbar region, soon assumes a more distinct shape 



