150 On Hippolyte fascigera and H. gracilis. 



be hoped that Mr. Gamble's researches may throw some light 

 upon this point. 



Nant y Glyn, Colwyn Bay, 

 Nov. 28, 1898. 



The Owens College, Manchester, 

 Nov. 29, 1898. 



Dear Mr. Walker, — 



I have read the MS. which you have kindly permitted 

 me to see. At Piel the regular habitat of fascigera is among 

 masses of the polyzoon Bowerbankia growing on the stems of 

 HaJidrys siliquosa. Adults taken from this habitat agree in 

 colour fairly closely with Gosse's description, but in captivity 

 among green weed change in colour to a greenish or greenish- 

 brown tinge. Should they then, as they do sometimes, shed 

 their fascicles, there remains no feature by which they can be 

 distinguished from typical varians. 



The young fascigera may inhabit the same Bowerbankia, 

 and are then freckled with brown and reddish spots on a trans- 

 parent ground. But, in addition to this variety, specimens 

 taken from fine plumose red weeds are lined and barred with 

 red. Others, again, have a densely pigmented sheath of 

 brown or black colour to the alimentary canal and two broad 

 transverse bars of the same colour. Both this and the red- 

 lined variety are also found in specimens of H. varians (that 

 is, in specimens with no trace of plumose hairs) in the same 

 haul. 



It would therefore appear that the colour of the young is not 

 distinctive. 



As to the plumose hairs themselves, they are apparently 

 normal structures, though not always symmetrically placed in 

 the segments in which they occur ; and if Gosse was right, as 

 I believe he was, in considering them deciduous structures, I 

 think we ought to have more evidence before considering 

 them to be aids in protective mimicry. 



I ought to add that the subject did not occupy my attention 

 when working at Piel as fully as it does now, and therefore 

 the observations I made should be considered as preliminary 

 to a fuller treatment of the subject. 



I am, 



Yours truly, 



F. W. Gamble. 



