174 ESCHRICHT ON THE 



ossified, and that especially all the extremities of the phalanges usually remain cartilaginous 

 throughout the aiiinud's life, by which means the whole fin must needs preserve a high degree 

 of flexibility, united with elasticity. In the individual whose pectoral fin forms the subject of 

 this description, the ossification had proceeded only very little even in the centre part of the 

 phalanges, as it will be seen in the woodcut above, and that this must partly be ascribed to the 

 young age of the individual, may be concluded at once from the facts that of the five bones of 

 the carpus, it is only the one marked by 1, that showed traces of an osseous nucleus, and that 

 the epiphyses of the long bones of the arm w^ere still entirely cartilaginous. But even in 

 old and full-grown small killers, of which the three brachial bones wei'e already completely 

 ossified, for instance, in Mr. Benzon's twenty-one feet long specimen, the ossification in the 

 five carpal bones appears only in as many osseous nuclei, irregular in their circumferences, 

 which were so far from being placed in immediate contact with one another, that the 

 cartilage had still a decided superiority in this part of the hand. In the phalanges, the ossification 

 appeared to be almost as incomplete. It is true, that even in the young individual, an osseous 

 nucleus was visible in the centre of every one of them ; in most of them it occupied 

 about half their length, in a few of them even two thirds ; but especially in the most external 

 phalanx of each finger and in both phalanges of the fifth, finger, it appeared outwardly only iu 

 about the same way as in the carpal bone marked by 1, that is, as a very small osseous 

 flake in the very centre ; and in two of the metacarpal bones, it had only reached the ulnar and 

 not the radial margin ; in the third, fourth, and fifth phalanges of the second finger, it had, on 

 the contrary, only reached the radial, and not the ulnar margin. This peculiarity we might also 

 feel inclined to ascribe to the youth of the individual, but it is still to be found in very old 

 individuals, especially in Mr. Benzon's, and must accordingly be considered as a character of 

 the species ; in the third, fourth, and fifth phalanges of the second finger of the latter 

 individual's pectoral fin, the ossification, always beginning in the centres of the phalanges, had 

 still only reached the radial margins of the bones. This state of imperfect ossification is evidently 

 closely connected with the peculiar breadth of these bones in the killers, and may, accordingly, 

 be reckoned among the characters derived from the pectoral fins. 



On account of the imperfect ossification of the bones of the manus of the killers, theii' 

 pectoral fins are liable to shrink very much in drying, so that they become still far" 

 shorter in proportion to their breadth than they are in their fresh state ; some allowance must, 

 therefore, always be made in measuring old skeletons. The pectoral fin of Mr. Thomsen's 

 thirteen feet long specimen was found between the 13th of June, 1855, when it was measured 

 and drawn, and the 4th of April, 1SG2, when it was measured again, to have shrunk to such an ex- 

 tent, that the humerus and the fore-arm, from being 10" 3'", had become only 9" long; the carpus 

 and manus had shrunk from a length of 12^" to 7^" ; and the manus from a breadth of 11" to 

 7" 1 V". In order to preserve the immense pectoral fins of Mr. Benzon's specimen in their original 

 form, they were, when prepared, fastened to an iron frame by strong nails ; but they were torn 

 by the nails while drying, and the whole arm was found to have lost a couple of inches in 

 length, and one inch in breadth, after which they were again nailed to the frame to prevent as far 

 as possible their further shrinking. 



By their powerful and broad pectoral fins, the killers are most directly opposed to the ca'ing- 

 whales, whose pectoral fins are remarkably long and narrow ; but these two genera of Delphinoids 

 are, on the contrary, tolerably similar to each other in the form of the vertebræ and that of the 



