PLATANISTA. 537 



eleventh transverse process. In some cases there are ten ribs on one side and eleven 

 on the other, following the foregoing arrangement. 



In a newly-born individual before me, there are only ten ribs on either side, and 

 neither of its terminal ribs touches the eleventh transverse process, but in a foetal 

 skeleton both of these are closely bound down to the eleventh process, from which a 

 rather long piece of cartilage projects outwards and backwards. 



Eour pairs of ribs are articulated to the sternum, cartilaginous in the young 

 but ossified in the adult condition, separated, however, from the vertebral ribs by an 

 intermediate piece or cartilage, as already stated. 



The scapula has its posterior border on a line with the posterior margin of 

 the sixth rib, its hinder angle being on a level with the middle of the rib. The 

 anterior angle of the scapula (process) is on a line with the anterior margin of the 

 arch of the fourth cervical vertebrae, and its superior anterior angle is opposite to 

 the arch of the fifth cervical, and the highest point of the bone is on a level with the 

 spinous process of the first dorsal in a young individual. 



The diaphragm is attached on a line with the inferior border of the sternum, 

 running along the inferior margin of the cartilage of the fourth rib, from thence 

 on to the apices consecutively of the free osseous ends of the fifth to the eighth 

 rib inclusive. It then passes across the ninth rib a short distance above its apex, and 

 from that crosses the tenth rib obliquely a still further distance above its apex, pass- 

 ing transversely across from side to side in an arch between the tenth and eleventh 

 dorsal vertebrse. 



Sternum (PL XXXIX, figs. 5, 6 & 7). — The presternum is large and broad^ 

 generally more or less notched in front, with convergent or lateral borders and a 

 transversely broad, abruptly truncated posterior extremity ; it has a general resem- 

 blance to the presternum of Fhyseter macroceplialus, if the fontanelle and mesial 

 suture of that presternum were fiUed up. It is subject, however, to great variations 

 in its anterior border, depending on the degree to which the cartilaginous interval 

 has filled up. In adolescents, it frequently forms a deep notch anteriorly. There 

 is no trace of the process which in the dolphins and porpoises occurs behind the 

 articulation for the first rib. The breadth of the presternum posteriorly equals 

 one-half of its greatest breadth between the articulation of the two first ribs, and 

 the mesial length is one and a haK as long as the posterior breadth. It is slightly 

 concave on its inner aspect and convex externally, and in an adult female there are 

 distinct indications on the same aspect of the mesial sutural line of the two original 

 elements. The facet for the first rib is borne on a slight projection of the anterior 

 angles of the bone and looks backwards and outwards. The position of this rib, 

 however, would appear to be variable, because in a young skeleton presented to the 

 Medical College, Calcutta, by the late Dr. Palconer, the first rib on the right side is 

 situated on the lateral border of the presternum, if anything, below its middle, far 

 remote from the anterior angle, and on the left side it is also removed from the usual 

 position, but anterior to the middle of the lateral border. There can be no error in 

 this observation because the skeleton is a natural one, none of the attachments of the 



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