184 ANCEID^E. 



In the earlier period of its parasitic life, the female 

 takes a green colour, which at a later stage deepens into 

 a bright blue. We speak of the common species round 

 our coast, to which Montagu gave the specific name of 

 caruleata. M. Hesse has figured one of a brilliant red ; 

 we have never seen such, but it is not improbable that 

 some species may change in their colour, which most pro- 

 bably varies with the condition of the food, for we have 

 taken them white, grey, green, blue, and brown. 



An examination of the material confined within this 

 portion of the pereion shows it to consist of oil and fat 

 globules, and we have been able to determine that it is 

 intimately associated with the nourishment of the animal, 

 since by keeping them without food the coloured mass 

 decreases in size. It is such an animal that Mr. Spence 

 Bate figured in his paper " on Praniza and Anceus" 

 "Annals Nat. Hist." for Sept. 1858, where he observes, 

 " After a few days the blue mass, which first appeared to 

 fill and distend the large segment of the pereion, gra- 

 dually diminished, apparently deteriorating. It recedes 

 first from the margin; in so doing it displays a series 

 of layers, placed one before the other, lying across the 

 animal. There were indications of these layers being 

 divided by cross sections. The relation that this co- 

 loured mass holds to that of the ova which, at a later 

 period, take its place, we know not ; but we are inclined 

 to believe that it is a reservoir of fat on which the animal 

 is supported during the period of incubation. 



We have not been fortunate enough to obtain em- 

 bryonic forms of the larvae so young as those figured by 

 M. Hesse (plate 1, figs. 5, 6, and 7), which, by their 

 single central eye and general form, resemble the larvae 

 of some entomostracous species of Crustacea, a form 

 that Dr. Fritz Miiller contends, with some apparent show 



