MARINE BIOLOGICAL STATION AT PORT ERIN. 37 



fine) and Neolepton obliquatum, the latter a species which 

 he added to the British fauna from Irish dredgings. 



It will be remembered that in our Sixth Annual Keport 

 (December, 1892), I gave an account of the colour varieties 

 of the little shore prawn, Hippolyte (or Virbius) varians, 

 and of their "protective" nature, as found on different 

 kinds of sea bottoms at Port Erin. A coloured plate (PL 

 VI.) showed the green form on the green plant Zostera; 

 a red form on the sea- weeds Delesseria and Bhodymenia; 

 and a dark olive brown form on the bushes of the brown 

 Alga, Halidrys siliquosa. Four possible explanations of 

 the facts were given, and it was stated that an experi- 

 mental enquiry into the matter was in progress. 



The following year, in the Seventh Keport (1893, p. 35), 

 the results of the experiments, so far as then obtained, 

 were given, leading to the conclusion " that the adult 

 animal can change its colouring very thoroughly, although 

 not in a very short space of time." A short description 

 of the conditions of the differently coloured chromato- 

 phores or pigment cells of the skin during these changes 

 was given, and their microscopic characters briefly dis- 

 cussed. It was stated "it would be interesting to 

 determine whether .... the modification of the 

 chromatophores is due to nerve action and is dependent 

 upon sight, or is the result of the direct action of light 

 upon the integument," but no further experiments bearing 

 upon this point were then made. 



During the following year the experiments were repeated 

 at Port Erin, with practically the same results. Glass 

 jars, painted on one side, or covered with coloured papers, 

 as well as those containing coloured weeds, were used ; 

 and the prawns, while changing colour, were occasionally 

 examined under the microscope, and some coloured draw- 

 ings were made of the elaborately branched chromato- 



