248 THE COMPARATIVE MORPHOLOGY OF THE CRAYFISH. 



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

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



\ 



Fig. 63. Camharus.Clarhii, male (^ nat. size), after Ilag-en. 



of the absence 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 



