Observations on a rare British Dolphin. 615 



are truncated. From an attentive examination of these in- 

 struments it would appear that when the teeth originally 

 pierced the gum, they had a conical form, with sharp-pointed 

 summits, which have, however, been subsequently worn down 

 by friction against their antagonists of the opposite jaw. — 

 Although the teeth are disposed in distinct alveoli, set apart 

 from each other, so as mutually to lock into the spaces which 

 intervene between them, still nevertheless, the eleven anterior 

 molars have lost at least one half of the original length of 

 their crowns by this denuding process. The anterior aspect 

 of the teeth of the lower jaw, and the posterior surfaces of 

 those of the upper, likewise have a portion of their enamel 

 and ivory obliquely chiselled away, in consequence of the an- 

 tagonising teeth having frequently rubbed against each other. 

 These instruments are nearly all of a uniform size through- 

 out, and are embedded, as I have already observed, in distinct 

 alveoli, at the distance of a quarter of an inch apart ; the four in- 

 ternal incisors of both jaws are much smaller than the others, 

 and the two central teeth appear almost rudimentary. The 

 truncated summits of the molars look obliquely downwards 

 and inwards ; and this natural section displays to great ad- 

 vantage the rind of dense enamel enclosing the concentric 

 rings of ivory. This substance, however, has lost its natural 

 cream colour, and become much darkened from exposure to 

 the air and water. 



It may be very justly asked, how does it happen that teeth 

 which lock into corresponding spaces of the opposite jaw, 

 become thus blunted ? To solve the problem it was neces- 

 sary that a careful examination should be made of the form of 

 the condyles of the lower jaw, and the glenoid cavity of the 

 temporals ; for it is evident that in order to effect the abra- 

 sion which I have described, it was necessary that the teeth 

 should have frequently opposed their crowns to each other, 

 and that there may be in the articulation of the lower jaw of 

 this species a special provision for vertical and lateral move- 

 ment ; and it may likewise admit of motion in the anteropos- 

 terior direction. In consequence of the condition of the parts 

 concerned in these movements when I received the specimen, 

 it was impossible to ascertain their anatomical structure. 



Since the above was written, I have had an opportunity of 

 consulting the 4th vol. of Palmer's edition of Hunter's works, 

 with notes by Professor Owen. At page 334 that learned ana- 

 tomist observes, — " the small bottle-nose whale of Hunter is 

 not the common dolphin, Delphinus Delphis, Linn., but the 

 Delph. Tursio, Fabr., as is shown by the skull and other parts 



