[Reprinted from THE AMERICAN NATURALIST, Vol. LI., May, 1917.] 



A CASE OF REGENERATION IN PANULIRUS ARGUS 1 



THE occurrence of regenerative processes in the Crustacea has 

 been a matter of record for a number of years, 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, e. g., in the fourth pair of appendages of the crayfish Cam- 

 "barus. 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 rostrum was entirely miss- 

 ing. The carapace around the base was jagged and rough, as 

 though the break had been recent ; but "a thin, soft membrane had 



1 Contributions from the Bermuda Biological Station for Research, No. 58. 



