286 DISCOVERY REPORTS 



The above tables have been drawn up for two purposes : (a) As a criterion of the 

 alterations in bodily proportions which occur as the total length of the whale increases. 

 (b) To provide a standard of comparison between the whales of South Georgia or 

 South Africa and the whales of any other localities. 



The first object is considered below. As regards the second, the tables have been 

 prepared to provide for such cases as that of an investigator who, having procured a 

 number of measurements of Blue whales from a locality in some other part of the 

 world, wishes to ascertain whether these whales differ in any way from those of the 

 South Georgia or South African region. Such measurements would be compared with 

 averages given in the table under the appropriate whale-lengths, but it would also be 

 required to know how much deviation could be allowed for individual variation. For 

 this reason the maximum and minimum readings of the measurements from which 

 each average is calculated are quoted in the table in addition to the average figure itself. 

 The value for this purpose of these maxima and minima is of course dependent on 

 the number of readings from which they are taken and the number of readings is there- 

 fore also quoted in each case. Under some whale-lengths the number of readings is 

 insufficient to show the extent of deviation which might occur, but by reference to 

 other columns there would be no difficulty in forming an idea of how much margin 

 should be allowed for individual variation. In this way a series of measurements 

 of even a single whale from some other locality could be profitably compared with the 

 averages given in the tables. 



Comparisons of bodily proportions are in general best made by reference to the 

 tables themselves, but the variations of the bodily proportions according to the length 

 of the whale are more conveniently shown by means of charts. In Figs, i to 23 the 

 averages shown in the table are plotted for each metre of whale-length in the case of 

 measurements 3, 4, 5, 6, 8, 10, 11, 12, 13, 18, 20 and 24. The other measurements do 

 not show any definite variation with the whale-length or other points of interest. 



The figures show in the first place no significant diff^erence in the shapes of the curves 

 for the two sexes except in the case of No. 13 (anus to reproductive aperture) to which 

 reference has already been made. In the second place no distinction can be drawn 

 in respect of these curves between whales of South Georgia and South Africa, at least 

 so far as the majority of the graphs are concerned. There are some slight diiferences 

 between the whales of the two localities in respect of the interval between the anus and 

 reproductive aperture in males (Fig. 19), the length of the flipper (Figs. 20 and 21) 

 and the depth of the tail (Figs. 22 and 23), but these are really very slight and need 

 not be regarded as of any significance. 



With the exception then of the genito-anal measurements the averages for male and 

 female Blue whales may be considered together. The averages for foetuses have not 

 been included in the graphs as there are not yet sufficient data upon which to base 

 sound conclusions so far as they are concerned. 



It will be seen that in both sexes the percentage measurements referring to the 

 anterior end of the whale (see Figs, i to 10) show a more or less regular proportional 



