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THE AMERICAN NATURALIST [Vol. LI 



slightly affected, were crossed. Of the 29 offspring resulting, 

 17 showed the defect in a severe form, and 12* showed ohly small 

 blisters. A female w^hich had only one wing affected, was mated 

 to a male, one of whose wings was severely affected while the 

 other bore a very small blister. Of the 45 offspring resulting, 

 27 bore the defect in a severe form on both wings and 18 showed 

 small blisters again on both wings. 



Further experiments with this new character were under way 

 when thr work was st(>p[)cd by the mobilization of the Militia in 

 June. The work witli these flies, however, is again being 

 resumed. 



Theophilus S. Painter 



A CASE OF REGENERATION IN PANULIRUS ARGUS^ 



The occurrence of regenerative processes in the Crustacea has 

 been a matter of record for a number of j^ears, but the instances 

 have been mostly confined to the regeneration of appendages and 

 portions of the nervous system. Observations on the regeneration 

 of portions of the exoskeleton of the trunk are far less numerous. 

 The present observations on the regeneration of a portion of the 

 rostrum of Panulirus argus, the common crayfish of the Bermuda 

 Islands, were made during the summer of 1916 at the Bermuda 

 Biological Station. 



Panulirus argus when full grown is about 14 to 16 inches in 

 length. It lacks chelipeds, their place being taken by the ordi- 

 nary type of walking appendage. None of the walking append- 

 ages is provided with nippers, all being tipped with a single hook, 

 as, €. g., in the fourth pair of appendages of the crayfish Cam- 

 harus. The rostrum of Panulirus, instead of being a single 

 median projection, -consists of a pair of long (30-35 mm.), 

 sharply pointed spines, slightly compressed laterally, and grow- 

 ing out from the carapace just posterior and slightly dorsal to 

 the base of the eye-stalks. 



The animal in question was a half-grown male, eight and one 

 half inches long. When caught, June 20, the left spine (com- 

 pare figure and explanation > of the I'ostrum was entirely miss- 

 ing. The carapace around thr baso was jagged and rough, as 

 though the break had been rer. iit l)ut a thin, soft membrane had 



