446 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1920. 



pugnacious and swift blue crab is unable to hold its own, and the 

 powerful stone crab is almost extinct over part of its range, but the 

 small and comparatively helpless fiddler maintains its millions un- 

 diminished. There must be large numbers of young fiddlers growing 

 up each year to take the places of those that feed blue crabs and fishes. 



HOW EGGS ARE LAID AND HATCHED. 



A study of the female fiddlers shows that they produce and hatch 

 their eggs much as do all crabs and shrimps. The higher crabs 

 (Brachyura) differ most conspicuously from the lower crabs (Ano- 

 mura) and shrimps (Macrura) in the relative size of the parts of 

 the body. In the higher crabs the cephalothorax forms the boxlike 

 region that comprises most of the body. The abdomen is relatively 

 quite small and is carried permanently flexed under the cephalo- 

 thorax, which has a groove to accommodate it. The appendages of 

 the abdomen are usually concealed between it and the cephalothorax. 

 The abdomen of the male fiddler is narrow and bears only two pairs 

 of appendages. These are used to transfer the sperm to the female. 

 The abdomen of the female is much broader and it bears four pairs 

 of genital appendages. 



The female crab lays her eggs in the early spring. Hundreds of 

 them are laid at one time. As they pass from the oviduct they are 

 entangled in a sticky fluid that covers the genital appendages. This 

 fluid then hardens and the eggs are left hanging to the appendages 

 like many bunches of tiny purple grapes. The bunches are packed 

 very closely together, however, and there are so many of them that 

 the abdomen is pushed far out of its groove and hangs down from 

 the body. The color of the eggs is due to the yolk, which, instead of 

 being yellow as in the bird's egg, is a dark purple. The eggs were 

 fertilized as they were laid and at once begin to develop. As the 

 embryos are formed inside the egg shells the yolk is used up and the 

 color of the egg mass gradually changes from deep purple to light 

 purple and at length to a dirty gray. When the mass is gray the 

 embryos are nearly ready to hatch. The female aerates the eggs by 

 standing in the water and jerking the abdomen backward and 

 forward. 



Since the fiddlers may be supposed to be very prolific, one expects 

 on examining the droves during the spring and summer months to 

 find many of the females carrying eggs. On the contrary, however, 

 one may examine thousands of the females on the beach without 

 finding a single one egg-laden, or even dig them from their burrows 

 by the hour and find very few. This is due to the fact that one 

 searches the beach by day, and the only burrows whose locations are 

 shown by openings are those whose occupants are out on the beach. 

 When carrying an egg mass the females are clumsy. They run 



