PSEUDORCA CRASSIDENS. 209 



insignificant. Tke circumstance, that the process does not appear in exactly the same manner 

 on both sides in the Middelfart dolphin, would in itself warrant any misgivings as to its being an 

 important or constant feature, nor, indeed, do we find even a trace of it in the skeleton of the indivi- 

 dual found at Refsnæs; and the ca'ing-whale is exactly in the same case,for this peculiarityis found in 

 some individuals of this species, but is entirely wanting in others ; and thus, we suppose, it can hardly 

 be entitled to be considered other than a mere accidental, though, perhaps, frequent abnormality. 



The sternum consists of four pieces ; in the full-grown male from Middelfart the three 

 foremost of these are united into one bone, in which, however, we may still discern the limits 

 between the original parts tolerably well; the hindmost portion, on the contrary, though 

 completely ossified, is only moveably joined with the preceding ones. The four pieces of the 

 sternum of the individual found at Refsnæs are not yet ankylosed to one another, and the 

 hindmost piece is still only cartilaginous ; the sternum of the female drifted ashore at Asnæs 

 had been broken when' the animal was cut up, and I only succeeded in finding one of the 

 fragments. I cannot, therefore, state with certainty, whether in the last period of life all four 

 sternal bones become completely ankylosed, but it can hardly be doubted but that such 

 is the case. In the foremost piece, or manubrium, the surface turned upwards is longi- 

 tudinally concave, but transversely convex ; the surface turned downwards is, on the contrary, 

 longitudinally convex, and, especially in its foremost extremity, transversely concave, in its posterior 

 portion it becomes gradually more flat in this direction. Behind the place where the first rib 

 is attached to it, the margin of the sternum projects into a pointed angle which, however, does 

 not assume the character of a special process, to such a degree as in the ca'ing-whale, and still 

 more in the killers. Not far from its anterior edge, the manubrium is perforated in the mesial 

 line by an oblong hole of somewhat different size in the different individuals, and, in the old 

 individual from Asnæs we find, a couple of inches behind this, another much smaller hole, 

 of which, however, nothing is to be seen in the two other individuals ; both holes are of course 

 indications of the original ossification of each of the sternal bones from two centres situated side by 

 side. Of the most nearly allied forms, the ca'ing-whales are also provided with the foremost 

 of these holes, but in B. griseus it is wanting, according to the statement of Cuvier, nor do 

 I find any traces of it in the Orcas, but as may readily be supposed, this hole is not a 

 character of particular importance ; it may be found in forms which difi"er very much in other 

 parts of their skeletons, and it may be wanting in one or the other of two nearly related forms. 

 I find it in a Lagenorhynclius, and in the common poi-poise ; it is further to be found ni 

 DelpJdnus delpJns ; on the contrary, it is wanting in D. tursio, in the platanista, the narwhal, and 

 the beluga. In the Refsnæs dolphin the individual pieces of the sternum are considerably narrower, 

 and, especially the second one, comparatively longer, than is the case with the male found at 

 Middelfart, and thus the sternum seems to change its form pretty much with age. I shall only 

 add still that an asymmetry similar to that which appears in the skull, pervades the whole 

 sternum ; for this bone, but particularly its anterior portion, has like the skull, a slight but 

 perceptible twisting from the right to the left. I do not, however, mention this asymmetry as 

 something pecuhar to this dolphin ; the same appears more or less distinctly in other species also, 

 and is, perhaps, even the rule, but this asymmetry in the dolphins, which may also appear in the 

 ribs being a little longer on the right than on the left side, has commonly been completely 

 overlooked, though, indeed, it is well deserving of attention.^ 



^ As far as tlie cachalots are concerned, Mr. William S, Wall has pointed out an obliquity also 



