354 CETACEANS. 



respect of their mode of implantation in the jaw they offer in the 

 Cachalot a condition intermediate between that of the teeth of the 

 extinct cetaceous-like Ichthyosaurus and the piscivorous Delphinus ; 

 they are lodged in a wide and moderately deep groove, imperfectly 

 divided into sockets, the septa of which reach only about half-way from 

 the bottom of the groove. These sockets are both too wide and too 

 shallow to retain the teeth independently of the soft parts, so that 

 it commonly happens, when the dense semi-ligamentous gum dries 

 upon the bone and is stripped off in that state, that it brings away 

 with it the whole series of the teeth, like a row of wedges half- 

 driven through a strip of board. A firmer implantation would 

 seem unnecessary for teeth which have no opponents to strike 

 against, but which enter depressions in the opposite gum when 

 the mouth is closed. That gum, however, conceals a few persistent 

 specimens of the primitive fceta series ; these are always much 

 smaller and more curved than the functional teeth of the lower 

 jaw. One of the upper concealed teeth, which was removed by 

 Mr. F. W. Bennett from the gum of a large female Cachalot, is figured 

 of the natural size in PL 89, figs. 3 and 4 ; the latter shows a 

 smooth surface at the convex side of the crown-end which seems 

 to have been produced by contact with the end of the opposite 

 large lower tooth. The fang is contracted and the pulp-cavity closed 

 in the rudimental upper teeth. In two mature Cachalots which 

 Mr. Bennet examined he found eight of these teeth on each side 

 of the upper jaw ; they had a very shght attachment to the bone. 



There is a well-marked sexual distinction in the size of the 

 jaws of the Physeter macrocephalus, those of the mature female being 

 relatively shorter by full one third than in the male. There are 



exciting and dangerous occupation on one side of this very fine tooth ; the other side bears 

 the following inscription : — 



" The Tooth of a Spermatic Whale, 



That was caught by the Ship Adam's Crew, 



of Albemarle Point, and made 100 bis. of Oil. 



in the Year 1817." 



Below this inscription are two excellent figures of the Cachalot, one spouting, the other dead 

 and marked for flensing. 



