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two, then narrow, but become longer in the next two. So far, 

 they project horizontally, but the transverse process of the fifth 

 points considerably downwards, and has its extremity tubercu- 

 lated and hooked downwards and inwards, so that it almost meets 

 the chevron bones. The same general features prevail in the 

 sixth, and, in the subsequent caudal vertebrae, where the process 

 exists, it becomes gradually shorter, and terminates in a rough 

 tuberous knob. 



There are hypopophyses fused with the bodies of the second and 

 third caudal vertebras; and, abutting on the junction between the 

 third and fourth is a distinct and separate chevron bone, which is 

 perforated by a canal. These exist at each subsequent vertebral 

 junction, being very largely developed about the middle of the 

 caudal series, and their largely expanded ventral surfaces are rough 

 from the presence of grooves and ridges running in the direction 

 of the long axis of the body. The chevron bones exist quite to 

 the end of the tail, but, corresponding to the last three or four 

 inter-vertebral spaces, they are little more than rounded nodules. 



THE RIBS. 



PL v., figs. 1 and 2. PL VII., figs. 5, 6, and 8. 



There are fifteen ribs, of which seven are articulated to the 

 sternum. 



The first is a remarkable bone. (PL VII., figs. 5, 6 and 8). 

 Very short and strong, it forms a powerful buttress for the sternum; 

 it is very irregular in shape, being in general terms expanded at 

 each extremity and constricted in the middle, the constriction 

 being due to a deep notch on the anterior border ; or, the rib 

 might be described as being very abruptly bent on itself in such 

 a way that the sternal end points both forwards and inwards. Its 

 large, expanded and irregularly trihedral head is directly articu- 

 lated with the posterior surface of the laterally-expanded and 

 ventrally-projecting mass of the fused cervical group, which, at 

 this point, represents the sixth. It is also articulated with the 

 transverse process of the eight) i, of which the articulating surface 

 encroaches slightly on the body. There is also ligamentous 

 connection with the body and transverse process of the seventh 

 vertebra, the rib thus being very firmly fixed to a wide extent of 

 attachment. The sternal extremity, bent forwards and inwards, as 

 above mentioned, is flattened and very wide, and joins the lateral 

 edge of the presternum, along its whole length, to its junction 

 with the first segment of the mesosternum. (PL VII., figs. 5 

 and 6.) Sometimes there is complete ankylosis at this articula- 

 tion, the position of the junction being shown by a bony ridge, 

 and in one specimen, complete ankylosis has taken place on one 

 side only. 



