B 



Fig. 22. — Variation in relative growth in the female abdomen of fiddler-crabs 



(Uca pugnax). 



(A) Left, medium-sized crab (carapace breadth, 10 mm. ; abdomen, 6 mm., broad and reaching 

 the bases of the legs). Right, medium-sized crab (carapace breadth, n mm. ; abdomen, 5J mm., 

 broad, not reaching the bases of the legs). 



(B) Means (A — A) and extremes (B — B and C — C) of relative abdomen breadth in female crabs 

 between 4 and 14 mm. carapace breadth. There is a clear bimodality of mean abdomen size, with 

 marked heterogony between 8 and 11 mm. carapace breadth. 



35 



