96 IIE. W. H. FLOWBE ON THE OSTEOLOGY OF 



7 belong to the cervical, 13 to the thoracic, and 21 to the lumbo-caudal region. When 

 the vertebrae are placed in order, with their bodies in contact, the whole column mea- 

 sures 38-8". 



The cervical region, as in Platanista, occupies a larger proportional space than in 

 most other Cetaceans, being 3"3" long, or x§f o of the whole column. In a common Por- 

 IJoise, measured for the purpose of comparison, it is but i%%q . All the vertebrae are 

 distinct, as m Platanista, Beluga, and Monodon alone among toothed AVhales. 



The atlas (PI. XXVII. fig. 1), very large for the size of the animal, greatly resembles 

 that of Platanista, but is higher in proportion to its breadth. Its neural arch is strong, 

 and has on its upper surface a slight longitudinal ridge representing the spine. The 

 base of tlie arch is not perforated as in many Cetaceans, and the groove for the sub- 

 occipital nerve is but slightly marked. On each side, between the anterior and pos- 

 terior articular surfaces, are two rounded eminences, the rudiments of an upper and 

 lower transverse process. In Platanista there is only a single intermediate process (which 

 Eschricht considers to represent the lower process), but it is developed to a much greater 

 length. In Beluga both processes are present as in Inia, and upon corresponding parts 

 of the surface of the bone. As in the other Odontoceti having a free atlas, there is a 

 strong process developed from the hinder edge of the lower arch of tlie bone, which 

 passes under and articulates with the inferior surface of the axis (see PI. XXV. fig. 2). 

 This is bifid at the extremity, and much more powerfully developed than in the young 

 Platanista which served for comparison. 



The axis has a massive body, and a high neural arch. There is no distinct odontoid 

 process, but only a general (though strongly marked) prominence of the anterior surface of 

 the body, especially towards its lower margin. On the under surface of this there is a 

 large rounded articular facet for the inferior process of the atlas. This is continuous at 

 the sides vnih. the anterior articular facets, and would indicate a tolerably free motion 

 between the first two bones of the neck. In Platanista tliis anterior projection of the 

 body of the axis is still more strongly marked, forming a process quite comparable with 

 the " odontoid " of other Mammalia. In Beluga it is almost wanting. The other pro- 

 cesses of this vertebra differ somewhat in detail from those of Platanista. Tlie spinous 

 process is broad and bifid ; the posterior zygapophyses are much less prominent, and their 

 surfaces look more backwards. A proper transverse process can scarcely be said to exist. 

 There are, however, instead of the single, conical, backward-dkected process of Plata- 

 nista, slight rudiments of an upper and a lower process, with a groove between them, on 

 the hinder surface of the lateral wings of the bone which support the great articular 

 facets for the atlas. The posterior epiphysis of the body was not ankylosed. 



description, I must admit the possibility of some of them being lost ; but the circumstauccs under wliich the 

 skeleton was prepared render this, at the least, extremely improbable. When it arrived in this country the 

 vertebrae were all united by their natural ligaments. Unfortunately they were not counted when in this state. 



