OCR Text |
Show 56 TROF. W. B. BENHAM ON THE OSTEOLOGY [Feb. 4, In the lower jaw of my specimen there are 13 teeth on each side; but in the Napier skull I find 15. The former is the number given by Wall and Krefft (3); the latter number is attributed to this whale by de Blainville and by Van Beneden & Gervais; while Flower & Lydekker, in their text-book on the Mammalia (first edition), give the number as from " 9 to 12." The Vertebral Column. Turning to the vertebral column, there are, in addition to the cervical mass of seven fused vertebrae, in which all trace of the separate vertebra? is absent, except of the 1st, 2nd, and 7th, 46 free vertebra?, of which 13 are thoracic, 9 are lumbar, 23 are caudal, of which the anterior 13 bear chevron-bones. In this enumeration I have followed Flower (on Physeter) in regarding as the first caudal that vertebra which carries at its hinder end the first chevron. It may be useful to give a summary of the formula of the free vertebra? according to previous authors \ Wall Yon Haast... Krefft v. Beneden 1 & Gervais J Total No. of free Vertebrae. 44 43 48 ? Thoracic. 14 12 13 13 Lumbar. 9 11 9 8 Caudal. 21 20 26 2 Chevrons. 13 8 10 2 With regard to the number of thoracic vertebrae, there thus appears from the accounts to be some slight discrepancy. Von Haast has already pointed out that the total number of vertebrae " 52," given by Wall, is due to an error in addition of the constituent vertebra?. Van Beneden & Gervais state (p. 351) that " whereas Wall describes 14 thoracic vertebra? and 14 pairs of ribs 2, we only count 13 on our figure." They suggest that perhaps the small 14th rib, being free and independent of the vertebral column, had disappeared during the preparation of the skeleton (C. niacleayi), and they found only 13 thoracics in the Japanese specimens described on p. 515. In the Parakanui skeleton there are only 12 pairs of complete ribs articulated with the vertebra?; but amongst the debris of the macerating-pan I found a small bone (PI. II. figs. 2, 3), measuring only 37 m m . in length by 9*5 m m . in greatest breadth. 1 Flower & Lydekker give C. 7 ; Th. 13 or 14; L.+C. 30 : total 50 or 51. 3 Wall found only the ribs of the right side. |