184 Prof. Eschricht on the Gangetic Dolphin. 



as formerly, be expressed, by calling the mammillary process the 

 articulating process; but this neither holds good in regard to 

 the anterior portion of the dorsal spine, where the mammillary 

 process suddenly makes its distinct appearance on the twelfth 

 vertebra ; nor behind from the beginning of the tail-part, 

 where these articulating surfaces altogether disappear, and the 

 so-called oblique or articulating processes lose their significa- 

 tion, and are nothing more than mammillary processes. The 

 mammillary processes, with the anterior articulating surfaces 

 and the isolated posterior articulating processes, appear gra- 

 dually to move higher up, backwards, on the thoracic and lumbar 

 vertebra? ; and on the last lumbar the posterior articulating sur- 

 faces are actually placed on the root of the spinous process itself. 

 But this is the direct consequence of the gradual change in the 

 form of the bony arc, from a broad, low and depressed bridge 

 across the spinal canal, to a narrow and high one (twice as high 

 as broad, on the last lumbar vertebra). 



The fourth point, however, has above all others attracted the 

 attention of modern zootomists, in its relation to the vertebrae 

 in mammalia. That the transversal processes (the upper or pro- 

 per ones) belong to the bony arc, is by no means to be considered 

 as a general rule ; quite the contrary : they belong to the bodies 

 of the vertebras, from the hindmost thoracic, throughout the re- 

 mainder of the spinal column, not only in whales, but likewise 

 in many other mammalia, especially as regards a portion of the 

 lumbar region*. Nevertheless, this difference in their origin, 

 has long ago justly created doubts, as to their being entirely of 

 the same signification. The transverse processes, which originate 

 from the bodies of the vertebra?, could not be put on a level with 

 the superior or proper ones ; but rather with the lower processes 

 of the cervical vertebra?. But in whales this view is opposed by 

 the manifest uniformity among the transversal processes of the 

 lumbar and the hindmost thoracic vertebra?, proceeding, besides, 

 not from the arc, but from the body of the vertebra? ; although it 

 is to their apex that the hindmost ribs are attached, in which 

 respect they appear, accordingly, not as the lower, but as the 

 upper or proper transverse processes, both in the skeleton of the 

 whale and of mammalia generally. The adoption of this view is 

 rendered still more difficult in the Bakenopterce, on account of the 

 want of neck and head in all the ribs, and the insertion of these on 

 the top of the transverse processes, of which the anterior rise from 

 the arc, the posterior from the body, the intermediate from both. 

 Nevertheless, as after all the view in question is assuredly the 

 correct one, its signification may be explained in the following 

 manner, according to the homologies propounded by Stannius 



* See Fried. Wilh. Theile, inMuller's Archiv, Jahrgang 1839, p. 108. 



