IQIQ-I ^^- Kemp : Notes on Crustacea Decapoda. 333 



It seems therefore that "high" males are very much com- 

 moner than " low" males, and that males (both forms included) 

 are nearly twice as abundant as females.' 



I am not at all certain as to the meaning of the dimorphism 

 in this species. Of both types of male there is a series ranging 

 from very small to full-grown specimens, a fact which perhaps 

 discounts the possibility that they represent breeding and non- 

 breeding phases. On the other hand it is very improbable that more 

 than one type of copulatory appendage can be employed in the 

 sexual process. In other species of Dotilla the appendage is gen- 

 erally blunt at the tip, resembling that of the '" high " male, a cir- 

 cumstance which points to the conclusion that the '' low" males 

 do not breed. 



The examples of D intermedia that I have seen from other 

 localities are mostly of small size and (determined mainly by the 

 form of the copulatory appendage) consist entirely of "■ high " 

 males and females. 



Several observations indicate that environment has a great 

 influence on species of Dotilla, its effects being shown both in the 

 size of the specimens and in the degree of development of the 

 secondary sexual characters of the male. Thus the individuals of 

 D. intermedia that we obtained in the outer channel of the Chilka 

 Lake in Orissa were all small and it was onh' with difficulty that a 

 few specimens were obtained which showed in an imperfect degree 

 the peculiar character of the '' high " male chela. In this locality 

 with its extreme seasonal changes in salinity, there can be little 

 doubt that the environment is unfavourable. A somewhat similar 

 instance has been noticed in D. wichmanni (see p. 330). 



At Chandipur it is clear that the environment is peculiarh' 

 {■SiYOVLXohle iox D. intermedia and that "low" males were found 

 here and not in any other place in which the species has been 

 collected, is perhaps in some way correlated with this fact. 



The following specirnens have been examined : — 



1 The abdomen in the genus Dotilla shows little difference in outline in males 

 and females. In determining the sex it is therefore necessary to examine the 

 pleopods, unless the specimens are ovigerous or with the male secondary characters 

 strongly developed. 



