THE SPERM WHALE 99 



are not shown graphically. Nos. 2 and 3 are short measurements taken from the tip of 

 the snout, a point not easy to define; Nos. 14 and 15 relate to the length and height of 

 the dorsal fin, more properly termed a dorsal hump in this species, the boundaries of 

 which are very vague and difficult to determine. The values obtained for these measure- 

 ments are therefore very variable from whale to whale and scarcely comparable : when 

 plotted they give very irregular curves which appear to be of little value. The values for 

 measurements Nos. 18 and 19 also give curves which appear to be of little significance. 



The sexual differences in the body proportions are brought out clearly by these 

 figures, in practically all of which the curve for the values from the females is very 

 distinct from that for the males. The curve for the females is above that for the males in 

 Figs. 4, 5, 7 and 8 showing measurements Nos. 7, 8, 10 and 11, indicating that for these 

 measurements the values in the female are relatively greater than in the male. These 

 measurements relate to the tail region (notch of flukes to dorsal fin, to anus, to umbilicus) 

 and to the distance between the centre of the eye and the centre of the ear. For measure- 

 ments Nos. 16 and 17 shown in Figs. 10 and 11 the values for the males given are 

 irregular curves, and those for the females do not differ widely. These measurements 

 relate to the size of the flipper. 



In the curves for the remaining measurements, Nos. 4, 5, 6, 9, 20 and 25, relating to 

 the head and anterior end of the body, shown in Figs, i, 2, 3, 12 and 14, those of the 

 females are below those of the males, indicating that for these measurements the values 

 for the females are comparatively smaller than those from the males. Similarly the 

 curves show that the values for measurements Nos. 9, width of flukes at insertion 

 (Fig. 6) and 13, the genito-anal distance (Fig. 9), are comparatively smaller in females 

 than males. 



A further point of interest presented by these curves is the fact that those for measure- 

 ments Nos. 4, 5, 6, 7, 20 and 25 (Figs. 1-4, 12-14) in general slope upwards from their 

 origin and those for measurements Nos. 8, 9, 10, 11 and 13 (Figs. 5-9) slope downwards 

 from their origin, showing that as the whale increases in length the relative size of the 

 head region increases and that of the tail region decreases. The rate of growth of the 

 body, therefore, decreases from the head region backward. There is some slight indication 

 that at extreme lengths the relative sizes of the head and tail regions become slightly less 

 and greater respectively, an event that may be correlated with the attainment of physical 

 maturity. These conclusions apply only to the males because the figures for the females 

 are too few to give curves long enough for their general trend to be gauged. 



The variations that occur in each measurement are shown in Table VI, in which the 

 values of each measurement, expressed as percentages of the total length, are divided 

 into arbitrary groups and the number of values falling into each group is recorded. These 

 data are shown graphically in Figs. 15-31, in which the curves all approximate to normal 

 frequency curves, each showing one large peak. Only in Figs. 24 and 31, for measure- 

 ments Nos. 1 1 and 25, notch of flukes to umbilicus, and height of head, are there indica- 

 tions of a pronounced shelf or second peak ; but the irregularities of these two figures can 

 scarcely be taken to be of any great significance. The data for males only are included in 



