100 STUDIKS OF TASMANIAN CETACBA, 



should not be paid to variability of colour as regards speci- 

 fic classification. The usually accepted definition as regards 

 the excernal colour of T. turdo is that the upper surface 

 is lead colour and the under surface white. Bedd'ijrd, 

 however, quotes ^^) an instance mentioned by Van Beneden 

 of specimens which were intense black, except for a white 

 streak on the ventral surface. The two specimens with 

 which this paper chiefly deals were of deep and polished 

 black on the upper surfaces, and slate coloaired on the 

 under surfaces. The colour being the same in both 

 sexes. 



As regards the vertebral formula, our specimens 

 showed C. 7.; D. 13; L. 17; Ca. 28-65. 



INTRODUCTORY AND PIIYLOGENETIC. 



As Anthropotomists are apt to refer rather loosely to 

 "vestigesi of the cartilagino'us cranium," we wish to make 

 our posiition quite clear prior to introducing the several 

 data that go to make up the present section of our paper. 

 If we assume that the history of the cartilaginous skiill 

 has, in the main, been correctly read, we still have to 

 face the fact that a cartilaginous tract, that by ostosis has 

 taken its place in the bony skull, may revert to its former 

 cartilaginous condition if the pressure of external evolu- 

 tionary conditions so compels it. In an instance such as 

 this is, it would be manifestly incorrect to call such a 

 structure "a vestige of the cartilaginous cranium," since 

 that summary method of dismissing the case would oc- 

 clude all the interesting facts of its racial history. As 

 it is, in this latter connection, •that we have to deal with, 

 part of a cartilaginous tract, in the Dolphin's skull, we 

 desire to avoid any ambiguity—hence this statement. 



Between the ossiRed pre-frontal bone (Ethmoid, of 

 Flower, and others), the frontal, and in part the nasals, 

 of a common Dolphin's skull there remains a strip of car- 

 tilage that mav, or may not, ossify. It is a moiety of 

 the ethmo-cartilage, but is not a relic of the cartilaginous 

 skull, since, as far as our researches go, it relates to the 

 ethmo-turbinals, which always ossify in part in intra- 

 uterine life, and, in totn, at a very early period — cei- 

 tainly before the septal portion of the ethmoid, or, as we 

 here term it, the coalesced pre-frontals. If no whale 

 ever ossified this cartilaginotis tract, and, therefore, never 

 showed any ethmo-turV>inals at all, we might assume this 

 to be a pre-mammalian racial character, and push the 

 ancesirv of the whales back to an eariy date, and call 



(8) Beddard: A Book of Whales, p. 275. 



