A CARCINUS WITH A RIGHT-HANDED WALKING-LEG. 



145 



from the back showed a big nerve entering the leg, and starting 

 from the right side of the ventral cord. But, strange to say, the nerve 

 does not leave the ventral cord at its side, but in the middle, passing 

 through the middle hole. I cut thick frontal sections of the ventral 

 cord. They show a small surplus half-ganglion on the right side, 

 between the claw-ganglion and the ganglion of the first walking-leg 



J3> 



Fio. 1. 



and not, as was to be expected, between the first and second or the 

 second and third leg-ganglion. 



There is no doubt that in this case we have neither a double-monster 

 nor an atavism, because the ancestors of the Brachyura never had 

 walking-legs on the abdomen. 



A second paper on this subject, containing minute descriptions and 

 several illustrations, will soon be published in a German journal, and 

 in that I will endeavour to give a theoretical explanation of this 

 abnormality. 



