198 CATODONTID^. 



be seen in the young animal upon removing the soft parts from the 

 interior of the jaw." — Bennett, Whaling Voyage, ii. 163; Proc.Zool. 

 Soc. 1836. 



" The number of the teeth varies greatly in different individuals, 

 and does not appear to be influenced by either age, sex, or size. 

 Amongst many Cachalots I find their variations in number to be as 

 follows : — 21 on one side of the jaw, 20 on the opposite ; 23-21, 

 22-22, 24-25, 22-23, 24-26, 23-24, 22-24, 19-20. Length of 

 male 60 to 76 feet ; of female, 30 to 35 feet. Foetus, 14 feet long 

 and 6 feet in girth." — Bennett, I. c. 154. 



M. de BlainviUe described what ho considered as two varieties, 

 observed in the lower jaws : — the first, from Cape Horn, has long, 

 slender, cylindrical, rather acute teeth, and the symphysis to the 

 twentieth tooth (figured Cuv. Oss. Foss. v. t. 24. f. 8) : the second 

 with 25 or 27 blunt and vertical teeth on each side, the symphysis 

 to the eighteenth tooth. — Ann. Anat. et Phys. ii. 335, 336. 



The ear-bones are figured by Camper (Anat. des Cetac. t. 23 

 & 25) and Cuvier from these figures (Oss. Foss. v. 376) ; they most 

 resemble those of the DeJphinidce, but are less elongate and less 

 bilobed posteriorly. The tympanic bone is small, scroll-like, oblong, 

 anchylosed to a somewhat similar-shaped tegmen tympani and pars 

 mastoidea (see Owen, Hist. Brit. Foss. Mamm. p. 526. t. 33. figs. 220 

 & 225 ; the figures are of the natural size ; not half the natural size, 

 as marked). They are from specimens sent by Mr. G. Bennett to the 

 Koyal College of Surgeons. 



The atlas is distinct ; the rest of the cervical vertebrae are anchy- 

 losed into one piece (Cuv. Oss. Foss. v. 346, t. 24. f. 12, 13). Ribs 

 14/14. Vertebra 60 (see Cuv. Oss. Foss. I. c. t. 24. f. 15-18). 

 Blade-bone higher than wide, with a large coracoid (7. c. t. 24. f. 11). 

 Humerus and cubitus anchylosed, short and thick (t. 24. f. 14). Os 

 hyoides very wide (Cuv. t. 25. f. 15?). 



There is the skuU of a foetus of this animal in the Museum of the 

 Royal CoUege of Surgeons : the bones are of a very soft structure. 

 The following are its measurements : — 



Length, entire 32 inches. 



Length of nose 20 „ 



Length of lower jaw 28 „ 



Length of symphysis 9-6 „ 



"Width at notch of nose 12-6 „ 



"Width of condyles apart 16-6 „ 



This foetal skull is most fully and accurately described as showing 

 the cranial organization of the present genus of Cetaceous animals 

 by Professor Owen (Cat. Osteol. Series, ii. 442). 



The length of the symphysis in the skull of the foetal Cachalot 

 is three-fourths that of the rest of the ramus. In the adult male, 

 the disproportionate growth of this part of the jaw leads to an 

 excess of the length of the symphysial part beyond the rest of the 

 ramus. 



