212 Records of the S.A. Museum . 



directed forwards: the tooth is set so that at first it grows very divergently in 

 relation to its fellow, thus well elearing the sides of tlic snout ; the sununits then 

 converge, and finally meet or eross as mentioned. An early funetiou of the ivory 

 tip may be to cut the gum, which would, apparently, 1)p opened on the outer side; 

 were the function of the tip to end there, we might sujipose that it would drop 

 off, much as does the thorn on the beak of an embryo chick. When, during the 

 growth of the tooth, the summit begins to curve oblic|nely over the snout, the tip 

 of the tooth tends to assume a more erect i^osition, until finally it becomes 

 subvertical. The successive deposits of tooth matter at the root are well seen in 

 the teeth in question, as shown in the figure, and are also illustrated in the drawing 

 of Krefft and Grav. 



Turner (^) gives a most exhaustive account of a young tooth — younger than 

 the one here described — from which it would ap])ear that it is not until a slightly 

 later development that the enamel tip or denticle takes on a downward position. 

 He describes the denticle as projecting outwards and slightly upwards; that is, 

 of course, in relation to the shaft, fang, or strap, and is true when the shaft is 

 but quite small, as in the "Challenger" example (fig. 15 aiul 16 ). As, however, 

 the shaft grows in an outward curve the denticle beconu's more and more deflected 

 from the plane of the shaft, until the latter begins to grow straight, whence the 

 curvature is changed, the strap curving inwards and ultimately over the beak, 

 when, as before stated, the denticle assumes an erect ])osition in relation to the 

 vertical axis of the skull. The downward aspect of the denticle in a tooth of the 

 age of that of the Kingston whale, when in position in the jaw, is relatively greater 

 than when held with the shaft in a vertical position, because the direction of the 

 root of the growing tooth, conforming to the slope of the mandible, is markedly 

 outward. Turner states that the denticle projects from about the middle of the 

 upper border of the fang. This is apparently correct only for a ver.v youlig 

 tooth, for what is the middle of the fang in a young example afterwards becomes 

 the anterior apical corner of the strap. The angle at which the denticle projects 

 after cutting the gum is thus indicated by the writer quoted : "It is set at such 

 an angle to the shaft as to be directed away from the animal 's snout, and towards 

 the water in which it swims." Seeing that the whale may be presumed to be 

 wholly immersed in water, this description is not very lucid; it was doubtless 

 intended to convey the information that the denticle was directed horizontally. 

 Tn our tooth, the direction when in situ is almost directly downwards. In Turner's 

 figure If), the tooth is illustrated as inclined backwards above, apparently to show 

 the condition of the ba.se, the "set" of the denticle being indicated in figure 16. 



(:•) Tiinicr, " Chalk'iiger " Report, i, Boik's of Cotaroa, 1880, p. Ri, pi. ii, fig. 15, 16. 



