OCR Text |
Show 1876.] DR. J. V. HAAST ON ZIPHIUS NOV^E-ZEALANDICE. 471 7 9. 11 19 46 In comparing this number with that observed in Ziphius australis, it will be seen that the New-Zealand species has three vertebrae less, viz. 9 thoracic instead of 10, and 19 caudal instead of 21, thus showing also some difference in the osteological structure of the two species. I may here observe that all the epiphysal plates of the vertebrae are so thoroughly coalesced with the rest of the body that the line of junction is not visible-a proof that the animal must have been not only adult, but aged. Cervical Vertebra. Of these the first four are entirely ankylosed, whilst the 5th, 6th, and 7th are free, thus having one free vertebra less than Ziphius australis, in which only the first three cervical vertebrae are united ; however, as this skeleton was derived from a young animal, this difference cannot be claimed as of a permanent character, until we know the skeleton of the same animal in a full-grown state. The atlas, which is 11*4 inches broad by 8*15 inches high, forms with the next two vertebrae one solid bone with a high crest; it is the largest of all the cervical vertebrae. The parapophyses (lower processes) in each of the coalesced bones, of which that of the atlas is the largest, are, with the exception of that belonging to the fourth, well developed. They decrease, however, gradually in size to the third, that of the fourth being of such small dimensions that it is an inch shorter than the same process in the preceding one, with which it is ankylosed at the upper and lower extremities, but not with the body. The fifth cervical vertebra is very narrow, 0*55 inch; it has moreover no spinous process above the arch, the summit of which stands two inches below the point of the spinous process of the four ankylosed vertebrae ; the parapophyses, although much larger than those of the fourth cervical vertebra, stand on the same line with them. The sixth cervical vertebra is a little broader than the preceding one ; there is only an indication of a spinous process above the arch ; the parapophyses are well developed, and advauce half an inch beyond those of the former vertebra. The seventh vetebra is slightly broader than the preceding one. It has a distinct spinous crest standing two inches above the arch. The lower process, or parapophysis, on each side has dwindled to a narrow tubercle, sloping upwards; the body of the bone has a well-marked articular surface for the head of the first rib, on both sides, which is situated between the well-marked upper transverse process (diapophysis) and the small tubercle representing the lower transverse process (parapophysis). These seven vertebrae have a length of 7*15 inches measured along the lower side of their main body. Cervical, Thoracic Lumbar Caudal |