THE CRUSTACEA 135 



exaggerated) adaptability of the chameleon to surround- 

 ings the influence of light is necessary ; that what the 

 animal sees acts on its nerve system, and indirectly controls 

 the pigment supply to the vessels beneath the transparent 

 cuticle. But, strangely enough, in Hippolyte the change 

 takes place in the absence of light or, at least, of light as 

 we know it. 



Specimens placed in vessels of water with weeds in con- 

 trast to themselves, at night, and shut in a close cupboard, 

 had changed their colours before morning. It might be 

 suggested that they feed upon the weeds, and that the 

 change of colour is due to food ; but such is not the case, 

 they do not eat the sea- weeds, nor do these give out a 

 coloration. This change is a problem which seems likely 

 to remain such. 1 



There is one of the mysids, named Mysis chcemaleon, 

 which is written of as having this faculty, but this is 

 an error. The mysids have no colour., evident as such, 

 only the translucent grey, with black pigment spots. I 

 fear that this mysis has been confounded with the long 

 and slender Hippolyte (virbius) viridis which it somewhat 

 resembles, and I regret to see this mistake repeated in such 

 a magnificent book as Wallace's " Darwinism." 



The next is Hippolyte fascigera. This is the smallest of 

 the genus, being but three quarters of an inch in length. 

 I have never noticed colour change in this one, but it- 

 imitates its habitat in a wonderful manner. 



It lives among the purple corallines, and a clump of this 

 plant held against the light shows the nodular arrangement 

 of the stems and the clubbed tips of the branchlets, with, 

 of course, clear spaces between them. 



Hippolyte fascigera has a transparent body, set with 

 dashes and dots of purple in such a way that it is possible 



1 I have recently had specimens change from brown to green, in a 

 white dish, with no stimulating colour present. 



