230 DISCOVERY REPORTS 



increases from 6-5 to 32-5 mm. This latter is by no means an extreme length, and it seems 

 not at all unlikely that large specimens may be eight years old or even older. 



The curves obtained for the male M. siibrugosa are closely parallel to those for the 

 female, but they indicate a slower rate of grov^^th especially in the first year. The initial 

 post-larval group in April-May has a slightly smaller modal length of 6-25 mm. The 

 curve in the circular graph (Fig. 12) shows the carapace length at the end of the first year 

 to be almost i2-o mm., 3-0 mm. less than in the female. The second half of the curve for 

 this year is based upon low figures, less than 10 per cent of the total catch in each period, 

 and one point, that for February-March at 13-5 mm., does not fall on the curve and, it is 

 felt, should be disregarded. Apart from this one point, the subhelical curve can be 

 drawn with reasonable confidence for the first five years of life, and is shown in the 

 figure for the first six. It shows that the male gradually overtakes the female in growth, 

 and the two sexes are roughly of the same length in their sixth year. As in the female, 

 growth continues after this, but the data are altogether too inadequate for discussion. It 

 can, however, be said that the largest specimens taken are usually male, and it seems 

 probable that the male normally lives to a greater age than the female. 



MUNIDA GREGARIA 



The data which can be used for inquiry into the growth of M. gregaria are not of such 

 an extensive or uniform character as those employed for M. siibrugosa. In the Falkland 

 Islands region this species was not met with during several months of the year and the 

 bulk of the material consists of the immature Grimothea stage, the adults seldom being 

 taken in quantity. In view of this it has not been thought advantageous to employ the 

 method used for M. siibrugosa. The graphs of carapace length for M. gregaria (Figs. 

 14-16) have not been drawn to give each curve of error in its entirety, but they have 

 been drawn with every attention to the form of this curve. 



Before considering the curves thus obtained for the specimens taken in the Falkland 

 Islands region an examination of those for the material from New Zealand waters will be 

 helpful.^ This material, comprising 137 specimens, 69 males and 68 females, was taken 

 in Otago Harbour at intervals varying from five to twelve days during the months 

 November 1932 to March 1933. The collections are well spaced, each month during the 

 period being represented by three or four catches, but the numbers in each catch are 

 small ; still, in spite of this, the homogeneity of the whole material gives it a value which is 

 lacking from the more extensive Falkland Islands material. The significance of curves 

 drawn from small samples is discussed by Wollaston (1929) and, accepting his views, it 

 is considered justifiable to draw conclusions even from these small samples. The 

 material was measured in the same manner as the Falkland Islands material, but it has 

 not been grouped into 2 mm. length classes and instead of percentages the actual 

 numbers are shown. Curves have been drawn for each of the five calendar months in 

 which specimens were obtained. 



Examining first the curves for the females (Fig. 14, right), a well-defined group is seen 



1 Procured by the late Mr G. M. Thompson as mentioned in the Introduction, p. 212. 



