Pearse—On the Habits of TJca Pugnax. 
799 
repulse he retired a little way and displayed his charms for 
a time before making another advance. Apparently he was 
attempting, as Chidester (’12) says, “to demonstrate his male- 
ness.” 
A little later in the same afternoon a small male Uca pugnax 
was seen to precede a female into his burrow just before the ris¬ 
ing tide covered it. Whether copulation takes place in the bur¬ 
rows or on the surface of the beach I cannot say, for no crabs 
were seen mating under natural conditions. I dug out a num¬ 
ber of burrows, but never found more than one crab at a time. 
High up on the beach there were many males (including the 
largest in the colony) and very few females; many of the 
females were carrying eggs. Lower down where the population 
was densest the two sexes occurred in about equal numbers. On 
July 12 and 17 I counted the fiddlers on a certain area. On a 
high, rather open place there were 146 males and 10 females 
(5 with eggs) ; two feet below (vertical) this there were 62 
males and 58 females. When a well populated area was care- 
' fully dug over, attempting to get a crab from every hole, 66 
males and 61 females (6 with eggs) were turned up on the lower 
beach; 10 males and 2 females above the high tide mark. From 
these results it would appear that there were more males than 
females, as Alcock (’92) believed to be the case in India, but 
there is a chance for error in the fact that the females are very 
easy to overlook, whereas a male can not well escape being 
seen. 
Despairing of observing the actual mating in the field, I car¬ 
ried over 125 Uca pugilators into the laboratory at different 
times and put them in glass tumblers, a male and a female in 
each. Only about half to three quarters of an inch of sea water 
was put in each tumbler, for it was found that many of the 
crabs died when they were completely covered. Under such 
circumstances I was able to observe five pairs copulating. Twp 
males were also observed while they were attempting to mate. 
Neither of them used the great chela, but attempted to climb 
upon the female and turn her over with the other legs. The 
position assumed during copulation is shown in figure 7. 
