MALE AND FEMALE CRAYFISHES. 7 



backwards with rapid jerks, proiDelJed by the strokes of a 

 broad, fan-shaped flipper, which terminates the hinder 

 end of the body (fig. 1, t, 20). In front of the four pairs 

 of legs, which are used in walking, there is a pair of 

 limbs of a much more massive character, each of which 

 ends in two claws disposed in such a manner as to 

 constitute a powerful pincer (fig. 1; 10), These 

 claws are the chief weapons of offence and defence 

 of the craj^fish, and those who handle them incautiously 

 will discover that their grip is by no means to be des- 

 pised, and indicates a good deal of disposable energy, 

 A sort of shield covers the front part of the body, 

 and ends in a sharp projecting spine in the middle 

 line (r). On each side of this is an eye, mounted on a 

 movable stalk (i), which can be turned in any direction : 

 behind the eyes follow two pairs of feelers ; in one of 

 these, the feeler ends in two, short, jointed filaments {2) ; 

 while, in the other, it terminates in a single, many -jointed 

 filament, like a whip -lash, which is more than half the 

 length of the body (5). Sometimes turned backwards, 

 sometimes sweeping forwards, these long feelers con- 

 tinually explore a considerable area around the body of 

 the crayfish. 



If a number of craj^fishes, of about the same size, are 

 compared together, it will easily be seen that they fall 

 into two sets ; the jointed tail being much broader, 

 especially in the middle, in the one set than in the 

 other (fig. 2). The broad-tailed crayfishes are the 



