— 120 — 



discernible. The seventh vertebra colli (fig. 19) conforms exactly to the type 

 of the 6th of Balaenoptera schlegelii Flower (4) p. 405 fig. 14 and 15. 



The dorsal vertebrae (vertebrae thoracis) (fig. 20 — 24) are generally 

 speaking much heavier than the cervical ones. The type is best rendered by 

 the 6th dorsal vertebra (fig. 22) which displays the features following: 



The centrum is stout, cylindrical with more or less round articular surfaces 

 which are either separated by a seam from the body proper or represent bony 

 epiphyses not yet incorporated with the main bone but in the nature of 

 loose, bony inter-vertebral discs. 



The large neural foramen has no longer so clearly the triangular shape 

 as in the cervical vertebrae but is more rounded. The spinous process is 

 long, flat and with right angles, slightly expanded at the top and slanted 

 backward; the lower and posterior basal end displays two divergent bony 

 plates, each of which possesses no more than a faintly developed knobby 

 prominence still representing the posterior articular process which, however, 

 hardly acts as such any longer. 



The anterior articular prominences on the contrary are strongly developed. 



The transverse processes are big, produced horizontally at right angles 

 with the longitudinal axis of the body and growing broader and stouter 

 towards the distal end. They also possess an articular facet directed exteriorly 

 and somewhat posteriorly for the costal capitulum. The body of the first 

 dorsal vertebra (fig. 20) is not much bigger than that of the last neck- 

 vertebra. In the next three dorsal vertebrae the dimension increases fairly 

 rapidly, after which the increase up to the last dorsal vertebra is slight though 

 regularly continuous. The neural canal remains practically constant for the 

 whole length of this section of the spine. The spinous processes, beginning 

 rather small immediately behind the last of the neck-vertebrae and having 

 at first a vertical direction, gradually increase towards the rear of the spinal 

 column, the position also assuming a more backward slope. 



The lateral process of the first dorsal vertebra shows to a marked degree 

 the compression in a cranio-caudal sense of the 7th neck-vertebra; in the 2nd. 

 dorsal vertebra this flattening is much less; it has disappeared entirely in the 

 3rd (fig. 23), the processus being more roundish. 



Henceforward, beginning at the 4th dorsal vertebra we see the beginning of 

 quite a different compression, namely in the dorso-ventral sense, which then 



