— 124 — 



little cross, has been reproduced separately in the upper-right hand corner, 

 with the front-surface directed upwards, so as to give relief to the small round 

 articular surface which was consolidated with the corresponding articular facet 

 of the preceding vertebra by cartilage. 



The remaining exterior margin of the bone of the front-surface is 

 furthermore enclosed With an extremely tough connective tissue, so that, 

 also as a consequence of relative smallness of these contact surfaces and the 

 comparative bigness of the inter-vertebral cartilage, the mobility of the 

 tail etid is considerable augmented. 



The chevron-bones (haemapophyses) (fig. 33) have the shape of a V, 

 and are attached, to the number of 19, to the lower end of the first 19 vertebrae 

 caudales. In order to show how the connection with the lower ends of the verte- 

 bral bodies is made, the 10th and 1 1th vertebra caudalis, reproduced in the late- 

 ral aspect in fig. 28,' have been once more copied in fig. 29, in the lower aspect, 

 so that it is now clearly show that the vertebral centrum possesses two larger 

 posterior and two smaller anterior articular facets, with which the upper ends 

 of the chevron-bones are articulated above. 



Furthermore, in fig. 29 we see the bony margins attached to the nether- 

 side of the vertebral bodies and forming the caudal canal aforementioned 

 which extends a long way back and is bridged or arched over each time 

 between two vertebral bodies by chevron-bones. This longitudinal sub-spinal 

 groove becomes naturally less pronounced towards the end of the caudal canal, 

 until on the last few caudal vertebrae (also the one marked with f ) there is 

 nothing left but a shallow depression, displaying right and left two perforations, 

 which features persist down to the hindmost vertebra of the tail. 



The chevron-bone occuring in fig. 29 bottom, between the 10th and Uth 

 vertebra caudalis has been furthermore reproduced in three different positions 

 (fig. 33) in order to bring out the character of this bone clearly. The lower 

 articular facets on the vertebral centra, which, as the illustratfon fig. 29 

 shows, are larger behind than at the front, become more equal towards the 

 tail, and consequently the chevron-bones are there suspended more nearly 

 from the middle. 



The first chevron-bone still consists of two bony plates converging 

 downwards but not yet coalescent there. The caudal canal is broadest here 

 and the distance between the bony plates forming the haemapophyses is largest. 



