LIFE HISTORY OF THE BLUE CRAB. 411 
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bay and the adjacent ocean are covered with dead crabs, mostly oviger- 
-ous females. All the observers mentioned the late fall as the time of 
such an occurrence. Moreover all those engaged in the crab fishery 
unite in saying that they have seldom, if ever, found an ovigerous 
female shedding her shell, and that the females which are found early 
in the season are of the virgin form. Evidently all the large females 
of the early spring are such as did not find a mate during the preced- 
ing season and have, therefore, still to fulfill their maternal destiny. 
It has been stated by Paulmier (1901) that the female crab does molt 
again after the eggs are hatched. His investigations made in the 
neighborhood of Long Island may indicate strikingly different life 
histories for northern and southern crabs, for the observations made 
at Crisfield prove quite conclusively that the female does not cast her 
shell after having produced her first and only lot of eggs. 
MOLTING. 
In practically all the lower animals whose bodies are incased in a 
tough unyielding covering extension in size and any change of form 
occurs not gradually and continuously, but suddenly and at intervals, 
and is always preceded by the casting off of the confining skin or 
shell, a process known as molting or ecdysis. The molting of the 
crab might have been dwelt upon more fully in the preceding para- 
graphs, but it is a matter of such interest and of such vital importance 
that it deserves to be considered by itself. It must suffice, however, 
to describe the process in the fully formed crab, and leave the subject 
of the larval molts for future investigation. : 
As the crab approaches the shedding period it begins to show its 
condition by various external ‘‘signs,” which are well known to the 
fishermen and are of great importance to them. The first indication 
is a narrow White line which appears just within the thin margin of 
the last two joints of the posterior pair of legs. This line 1s so nar- 
row and ‘so obscured as to be barely visible, but it is immediately 
detected by the expert, and the individual bearing it is classed as a 
‘*fat crab,” or more vulgarly as a ‘‘snot.” Within three or four days 
the white line gives way to an equally narrow and obscure red line, 
and a set of fine white wrinkles makes its appearance on the blue 
skin between the wrist (carpus) and the upper arm (meros). Such a 
crab is known as a ‘*‘peeler,” and may be confidently expected to cast 
its shell within a few hours. As the time progresses the marks 
become more and more evident, and a reddish color (especially in vir- 
gin females) begins to appear at the margins of the segments of the 
abdomen. Then, on the under surface of the carapace, extending 
from the neighborhood of the mouth around the sides and backward 
to the posterior margin, there appears a narrow fracture, so that the 
whole upper surface of the shell can be raised up from the back like 
