NORTHERN SPECIES OF OROA. 175 



head. This resemblance is especially produced by the neural spines being in general singularly 

 small in both species, especially from the middle of the lambar region, and by the neurapo- 

 physes themselves being comparatively high and narrow, so that the articular processes appear to 

 have advanced upwards in an uncommon degree and to be placed close to each other. Never- 

 theless, any of the vertebrae of an Orca may easily be distinguished from the nearest correspond-" 

 m<^ one of a ca'ing- whale by its greater circumference, especially as far as the body is concerned, 

 and that not only because the killers, generally speaking, are far larger animals, but also because 

 they are, at the same time, comparatively far more powerfully built. In every single part of the 

 vertebral column pecuUar distinguishing marks may, of course, also be pointed out, at least when 

 we have the objects themselves before us. Particularly, the well-known circumstance ought to 

 be remembered, that all the cervical vertebræ of the ca'ing-whales are ankylosed,^ or rather 

 forming one single bone, as they originally have formed one single cartilage ; whereas, the 

 seventh cervical of the killers is always completely free, and the fifth and sixth, at least as far 

 as their vertebral bodies are concerned. In dried skeletons of young individuals, it would 

 often seem as if only the atlas and the axis made one piece, but this is only in consequence 

 of the not yet ossified cartilaginous portions uniting the rest of the cervical vertebræ having 

 become dry and fallen out. As regards the dorsal vertebræ, we may, perhaps, be permitted to 

 mention still another distinguishing mark from the ca'ing-whales, though indeed only a nega- 

 tive one. For though in the latter genus the seventh pair of ribs, like the succeeding pairs, 

 are only attached to the transverse process of the corresponding vertebra, yet they seem originally, 

 like the six preceding pairs, to have been furnished with necks, only that these necks during the 

 process of ossification, have been separated from the ribs themselves and ankylosed with the 

 vertebra. In many cases, however, we only find slight traces of these strange osseous appen- 

 dages to the seventh dorsal of the ca'ing whale, but in the killer we find no traces of them 

 at all. 



The killers have either twelve or only eleven pairs of ribs ; sometimes (as in Mr. Thomsen's 

 specimen) twelve on one, eleven on the other side, a difference that seems to denote that the number 

 is not quite constant. The ribs are, on the whole, comparatively long, massive, and much curved. 

 The six foremost pairs are attached to the sternum by means of their sternal portions which form 

 separate bones, as is always the case in the toothed-whales. The ossification of the sternum 

 originates in four nuclei. In Mr. Thomsen's thirteen feet long specimen, the three foremost of these 

 nuclei are already very large, only separated from one another by cartilaginous transverse inter- 

 spaces ; but in the hindmost and more narrow part of the sternum the osseous nucleus has not 

 yet appeared. The foremost pair of ribs is attached to the sternum on a level with the fore- 

 most osseous nucleus, that is, to the perceptibly broader part of the sternum called the manu- 

 brium, the second, third, and fourth on a level with the cartilaginous transverse portions between 

 the osseous nuclei ; the fifth and sixth finally, to the posterior and more narrow part, that 

 was found entirely cartilaginous in the sternum of Mr. Thomsen's specimen. 



A pair of bones that deserves our particular attention in the skeleton of the Cetaceans 

 are the pelvic bones, for not only wiU they in general serve to determine the genus, if not 

 the species of the animal, fully as well as any other bone in the skeleton, the head alone 



^ [This statement is scarcely to be relied on ; compare what I have said on this point in the 

 following paper on Pseudorca : J. Reinhardt.] 



