15 



tectli in the upper jaw.* It may be some excuse foi- tin's commou 

 mistake, tliat we find tlie deficiency of upper teeth mentioned by 

 Cuvier in Ins " JCe^ne Animal,'" as, perhaps, the most palpable 

 distinction. In truth, however, scarcely any character of sperm 

 whales can be selected less peculiar than this, since the want of 

 teeth in the upper jaw is very common among the dolphins. 

 The genera Hyperoodo^i, Lacep., Zipliius, Cuvier, and Delpliinor- 

 liijncJius, Gray, have all no teeth in the upper jaw ; and even 

 such typical genera of Delphi ni dec as Beluga, Gray, Olohicepli- 

 alus, Lesson, and Grampus, Gray, have them early deciduous. 

 So far, therefore, as concerns this character, the cachalots are 

 nothing else than immense animals of the dolphin family. 



At least, there can be little doubt of the Gatodontidce or sperm 

 whales coming nearer to the dolphins, more particularly to the 

 genus Jlyperoodon, in structure, than to the toothless or true 

 whales, formiug Mr. Gray's family Balcsnidcc. One great dis- 

 tinction from all other Cetacea of the Catodontidcv, is the vast 

 concavity of the upper surface of their skull. Several kinds of 

 dolphin have the skull concave, but none have the hollow of such 

 capaciousness. This hollow, under the floor of which the brain 

 is lodged, is formed by an extension of the maxillaries, which 

 are so developed, as, together wdth other bones, to form a 

 semicircular wall, which in the Sydney skeleton has less of the 

 horseshoe shape than the head figured by Cuvier, in his " Ossemens 

 Fossil es.'^ 



* Beale says, that some sperm whales liave rudimentary teeth in the 

 upper jaw ; but if so, such animals must belong to a very different sjjecies 

 from our Sydney whale, which has not even the vestige of alveoles. Nor 

 has the skull of a very young sperm lately discovered on the beach near 

 Botany. However, it is right to remind those persons who may have it in 

 their power to investigate the matter, that Mr. F. D. Bennett says, that he 

 found eight rudimentary teeth oueach side of the upi^er jaw in two instances 

 of sperm whales, which teeth *' are not visible externally in the young 

 cachalots, but may be seen upon the removal of the soft parts from the 

 interior of the jaw." The entire length of these teeth was about three 

 inches ! Now, this story is not to be reconciled with the description of the 

 upper jaw of the sperm whale given above, and therefore, I suspect that 

 Mr. Bennett must have taken some kind of dolphin for a young cachalot. 



