rniA GEOFPEENSIS AND PONTOPORIA BLAINVILLII. 97 



The remaining five cervical vertebrae are compressed in the antero-posterior direction, 

 but less so than in most Cetaceans. They do not present the peculiar depression and 

 transverse extension characteristic of the cervical vertebrse of Platanista, but their 

 bodies are nearly circular in outline, and the height of the neural canal bears a more 

 considerable proportion to its breadth. The bodies increase but very slightly in 

 thickness from before backwards. The arches are wide and low, their sides meeting 

 above at very obtuse angle, and so narrow in the antero-posterior direction as to 

 leave spaces between them about equal to their own breadth. They increase but very 

 slightly in height from the third to the seventh, and possess but a mere rudiment of 

 a, spine, scarcely recognizable in the third, and but '2" in height in the seventh. The 

 anterior and posterior articular facets of the arches are well developed in all, and have 

 their usual relations. 



The transverse processes are, as usual, two on each side, upper and lower ; the upper 

 springs from the arch, the lower from the body of the vertebra. In the third vertebra 

 these two are very near together, and approximate at their ends so as to enclose an 

 oval foramen or canal '2" in its greatest diameter. On the left side this canal is com- 

 pletely surrounded by bone; on the right side it is not quite completely inclosed. 

 In Beluga similar rings are formed by the transverse processes of this vertebra, also in 

 the Platanista described by Eschricht, though in the College specimen there is but a 

 single broad imperforate transverse process. In the fourth vertebra the processes are wider 

 apart, short, and obtuse, and of about equal length ; a small elevation rises from the side 

 of the body of the bone, midway between them. In the fifth vertebra they are still 

 wider apart, owing to the upper one, which is short and conical, rising higher on the 

 side of the arch. The lower process is much larger, stouter, rounded at the end, and 

 directed backwards. Although upwards of I" long, it was evidently not fully deve- 

 loped in this immature individual, being tipped with cartilage. The prominence of 

 this process, contrasting with the almost rudimentary condition of all the others, is a 

 marked characteristic of the cervical region. In Platanista and Beluga, as in most 

 other Mammalia, it is the sixth vertebra which has the most largely developed inferior 

 transverse process, in the former very remarkably so. It is worthy of note, however, 

 that the Dugong {Halicore) agrees with Inia in this respect, as well as in many other of 

 the characters of the neck-vertebree. 



In the sixth vertebra, both upper and lower processes are small and conical. In the 

 seventh vertebra the upper process is more developed ; the lower one still exists, but 

 in quite a rudimentary state ; behind it is a shallow excavation for the head of the first 

 rib. The lamina of the arch of this vertebra are wider than in the others ; its spine, 

 as before said, is slightly higher; and the posterior surface of its body is transversely 

 extended. 



The thirteen thoracic vertebrae measure in length when placed in close contact 12-5". 

 Their bodies increase at first rapidly, then more gradually in length — the first mea- 



