Crustacea. 



149 



uncommon in Guernsey. And on one occasion only, I have 

 found the beautiful scarlet-and- white banded prawn "Lysmata 

 seticaudata" (whose habitat is supposed to be the Mediterranean 

 alone, and even there to occur rarely) at La Rocque point, 

 Jersey. 



In the " inferior" or "Sessile-eyed" Crustaceans, the pro- 

 portion of recorded forms found here, is as great as in the 

 above — only one or two of the Northern forms not being so far 

 represented, while on the other hand some forms (a consider- 

 able number, I believe) found here do not appear in the mono- 

 graphs, in fact there is yet much to be done in the identifying 

 and listing of this sub-class. 



For a study of the subject of evolution few groups of 

 animals present such an enticing field as does that of the 

 Crustacea ; the road whence, and the manner how, the present 

 forms have been reached being clearly mapped in the life- 

 history of each species. 



I do not for one moment mean to say, that a clear line of 

 descent, without a break, is observable here more than else- 

 where, but that here especially, we catch glimpses of the road 

 at points so little remote that we can more readily infer its 

 direction. 



I will roughly point out what I mean, by reference to the 

 relative life-history and family-history (Phyllogeny and onto- 

 geny) of one or two familiar forms. I will not enter into the 

 full details of the subject, for this would involve the entering 

 into such abstruse points, as for instance, the merging, in some 

 species of several developmental stages into one, — I should also 

 have to employ those aerial bridges across the unavoidable 

 chasms, which form the ground of objection of the an ti- evolu- 

 tionist. I will therefore just sketch a general outline of the 

 subject as far as it can be illustrated by the specimens before 

 us (in the museum cases), and as far as time will allow. 



Let us take as a type of the most highly-developed 

 species— our great edible crab. Just prior to its adoption of its 



