CRA YFISH. 

 THE APPENDAGES OF THE CRAYFISH. 



25 1 



No. 



Name. 



Function. 



Structure. 



Antennules (pre- 

 oral?). 



olfactory, 

 ear - sac at 



Antennae 



oral?). 

 Mandibles. 



(pre- 



ist Maxillae. 



2nd Maxillae. 



Tactile 



with 



base, 

 Tactile, opening of 



kidney at base. 

 Masticatory. 



Produces respira- 

 tory current. 



Two branches, but probably 

 not homologous with endo- 

 podite and exopodite. 



Small exopodite. 



Four joints, of which three 

 form the palp (endopodite 

 and upper joint of protopo- 

 dite). 



Thin single-jointed protopo- 

 dite, small endopodite, no 

 exopodite. 



Thin protopodite, filamen- 

 tous endopodite ; the 

 ' ' baler " is formed from 

 the epipodite, probably 

 along with the exopodite. 





19 



ist Maxillipedes 

 (foot -jaws). 



2nd Maxillipedes. 



3rd Maxillipedes. 



Forceris (chelate). 



Walking Legs 



(chelate). 



Masticatory. 



Fighting, seizing. 



Walking. 



Genital opening in 

 female. 



Genital opening in 

 male. 



Thin protopodite, small en- 

 dopodite, large exopodite. 



Two - jointed protopodite, 

 five -jointed endopodite, 

 long exopodite. 



Two - jointed protopodite, 

 large five-jointed endopo- 

 dite with strong teeth on 

 its ischiopodite, slender 

 exopodite. 



No exopodite. In the claw 

 the last joint bites against 

 a prolongation of the 

 second last. 



Without chelae. 



Modified swim- 

 merets in male ; 

 in female, rudi- 

 mentary. 



Modified swim- 

 merets in male, 

 normal in female. 



Swimmerets. 



Great paddles. 



(Serve in the male 

 ■< as canals for the 

 ( seminal fluid. 



/"Move slightly like 

 J oars, and carry 

 1 the eggs in the 



V female. 



Important in swim- 

 ^ ming. 



Protopodite and endopodite 

 form a canal ; no exopodite. 



All the three parts. 



