5^ 



THE CRUSTACEA 



The classification of the Branchiopoda commonly adopted differs 

 from that given below in grouping together the Anostraca, 

 Notostraca, and Conchostraca as a single order, Phyllopoda 

 (Latreille, 1802),^ distinguished from the Cladocera chiefly hy the 

 greater number of somites and appendages and by the prevalence 

 of metamorphosis in development. The groups of the Phyllopoda, 



Fig. 32. 



Folyartem la forcipatd, one of the Anostraca. x 5. (After Sars.) A, female, dor.sal view; 

 B, male, lateral view, a', antennules ; a", antennae, very small in the female but greatly 

 enlarged and three-branched in the male; f.a, "frontal appendage"; j), paired pene.s of the 

 male. There are nineteen limb-beaiing trunk-somites, followed, in the male, by six limbless 

 somites (besides the telson), of which the lirst and second are partly coalesced to form the 

 genital segment. In the female the limbless region of the trunk is unsegmented. 



however, differ among themselves in characters which are at 

 least as important as those separating the Cladocera from the 

 Conchostraca, and it seems desirable to recognise this by giving 

 them the rank of orders. 



1 Unfortunately some writers, following Claus, have transposed the uaine.s 

 Branchiopoda and Phyllopoda, applying the latter to the sub-class and the former 

 to one of its divisions, but this use is not sanctioned either by priority or by 

 universal custom. 



