126 PEAESE. 



number of fiddler-crabs to be seen along the edge of a small bay- 

 on the afternoon of May 20, as the tide was going out. Further- 

 more, even if the females to be seen were actually fewer than 

 the males, it could not be taken as proof that they were less 

 abundant ; for, as they use both chelse, they are able to feed twice 



Table III. — Showing sexes of fiddler-crabs in view as the tide was 

 going out. 



Time. 



Females. 



Males. 



p.m. 







4.30 



6 



1 



4.36 



12 



4 



4.44 



13 



3 



4.51 



14 



7 



4.58 



14 



7 



5.05 



13 



8 



as fast as the males ; therefore, they could obtain the necessary 

 food in a shorter time and would be able to pass longer periods 

 sealed in their burrows. The crabs along the estuaries of Manila 

 Bay, in the opinion of the writer, are about equally divided 

 between the sexes. However, the males are more active and 

 conspicuous and might easily impress an uncritical observer as 

 exceeding the females in number. 



The behavior of the sexes toward each other is of particular 

 interest. It was with deep regret that the writer was obliged to 

 forego the pleasure of watching the fiddlers during the breed- 

 ing season. Mating probably occurs at Manila "in the colder 

 months," as Alcock ('92) has observed in India. No females 

 were observed during the hot season (May 1 to August 1) that 

 were carrying eggs or young, nor were any very immature 

 fiddlers seen. The males frequently fought each other and stood 

 at "attention" with outstretched chela on the top of some 

 eminence (fig. 6), apparently awaiting a combat, but only a 

 few cases of courting were observed. 



The behavior of the sexes during courtship is important on 

 account of its bearing on sexual selection. In one instance 

 observed by the writer, the male waved his large chela and 

 danced actively about the female with his back toward her for 

 about five minutes. The female meanwhile hung around the 

 mouth of her burrow, always keeping her face away from her 

 suitor, while he made frequent attempts to climb over her back- 

 ward. Although the male was unsuccessful in his efforts, he 

 never turned his face toward the object of his attention. A 



