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DR. W. A. CUNNINGTON ON 



is shown to possess not only a considerable number of character- 

 istic species, but a much richer fauna than the other great 

 African lakes, with which we may reasonably compare it. In 

 the adjoining table of distribution, these facts are expressed iu 

 graphic foi'm. 



Table of Distribution. 



Taking a general survey of the specimens which have been 

 examined, there are a few points which call for mention. 

 Speaking broadly, there is no great disparity in the numbers of 

 the two sexes in the collection. Only in the case of Argulus 

 rubropunctattts was there a marked preponderance of one sex, 

 a total of 45 males accompanying 15 females. There were 

 occasional isolated individuals, but both sexes were usually 

 associated on one host. As a rule, females were larger than 

 males, which seems to be commonly the case. 



It is difficult to understand why, in certain species, the relative 

 size of the suckers is different in the sexes. The most striking 

 example is that of A, striatus, where a series of measurements 

 gave the following results: — Sucker diameter in males •12-- 14 

 of breadth of carapace : in females, 'M-'IS of breadth of cara- 

 pace. Such a degree of variation cannot, in this case, be merely 

 an index of carapace diversity in the sexes — short and broad, 

 for instance, contrasted with long and narrow — since these males 

 and females are very similar in this respect. As a rule, where 

 we have sufficient evidence to go upon, the male appears to have 

 a smaller sucker in pi'oportion than the female. 



Concerning the relations of these forms to their hosts, some 

 further observations may be offered. Both in Victoria Nyanza 

 and Tanganyika, the smaller fish appear to be relatively little 

 infested by the parasites. These were most frequently observed 

 upon large fish, and particularly on Siluroids, the scaleless nature 

 of which must render them especially liable to attack. Large 



