HIPPOLYTE VARIANS. 605 



lobes. Another variety (PL 33, fig. 7), found amongst the 

 miniature forests of Bowerbankia, is speckled and barred 

 with light brown on a transparent ground, spotted with 

 bright yellow when seen against a dark ground. This 

 variety possesses, in summer, the plumose hairs on the 

 carapace and abdomen, supposed formerly to be a charac- 

 teristic of Hippolyte fascigera. In December, however, 

 these hairs are not usually present. Other colour forms 

 are seen in yellow and yellow-barred specimens ; in brown 

 prawns spotted with lighter markings ; in the dark opaque 

 blue and the transparent, almost colourless or greyish forms, 

 the exact habitats of which have not yet been discovered. 

 Indeed, it may be said that the forms are infinite in variety ; 

 yet it would seem to us that a fuller description even than 

 that here given is very necessary before it can be deter- 

 mined with certainty whether any given form follows an 

 ordained colour sequence, whether change of surroundings 

 can permanently modify this sequence, problems which we 

 hope ultimately to resolve. 



Hippolyte varians exhibits a certain sexual dimorphism 

 both with regard to size and to colour. This may be ex- 

 pressed by saying that the males are on the average much 

 smaller and less elaborately patterned than the females, 

 which are more resourceful in adjusting their coloration 

 to that of their surroundings. From the point of view of 

 " protection," this difference is only what might be expected 

 from the greater sluggishness of the female, burdened as she 

 almost invariably is with a load of eggs or developing larvae. 



Section III. 

 ^^ Chromatophores" and other Colour Elements. 



It has been observed in the preceding section that the 

 colours of the bands in red- and other lined Hippolyte 

 change according as transmitted or reflected light is used for 

 the examination. We now consider the pigments to which 

 these colours are due and the nature of the colour elements, the 



VOL. 43, PART 4. — NEW SERIES. U U 



