44 W. Faxon — Dimorphism in the Genus Cambarus. 



Such a change as this connected with the reproductive 

 periods is unparalleled, so far as I know, among the Inverte- 

 brata; and even among the Vertebrataf the cases of partial 

 atrophy of the generative organs or shedding of antlers (as in 

 the stag) after the rut is over are hardly comparable. 



At the time I had the specimens alive my attention had not 

 been drawn to the questions relating to the two forms of the 

 males, so that I failed to make anatomical examination, and 

 the specimens have now lain too long in alcohol to be service- 

 able for internal dissection. I hope, however, that naturalists 

 who are more favorably situated will be able to throw more 

 light on this subject. 



I will add that the males of extraordinary size which I have 

 seen, are all of the "first form." Do these very old individuals 

 cease to moult? Do they become permanently capable of re- 

 production ? 



Museum of Comparative Zoology, Cambridge, Mass., Nov. 12, 1883. 





