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 



Fig. 63. Camharus Chirk'd, male {h 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 



