248 THE COMPARATIVE MORPHOLOGY OF THE CRAYFISH. 



extent than those do from one another. The gills are, 

 in fact, reduced to seventeen on each side, in consequence 



I 



Fig. 63. Camharus Clarkii, male (A nat. size), after Hagen. 



of the ahsence of the pleuro-branchia of the last thoracic 

 somite ; and there are some other differences to which 

 it is not needful to refer at present. It is convenient to 



