THE BRANCHIOPODA 31 



in 1900 by Lilljeborg, who bad made important contributions to 

 the subject so long ago as 1853. 



MORPHOLOGY. 



The Branchiopoda present considerable diversity of general 

 shape. In the Anostraca there is no shell-fold, and the elongated 



Fin. 16. 



T^epidnrits glacialia, one of the Notostraca. x 2. (After Sars.) Dorsal view on the left, 

 lateral view on the right. In the latter, one-half of the carapace has been cut away to show 

 the segmentation of the trunk and the apj>endages. On the dorsal surface are seen the paired 

 eyes with the "dorsal organ" behind and between them, the median dorsal ridge of the 

 posterior part of the canquice, and the two transverse grooves just behind the eyes. 



body, composed of many distinct somites, has an almost vermiform 

 aspect (Fig. 15). The flattened natatory feet are more laterally 

 placed than is usual in Crustacea, increasing the resemblance to 

 the Chaetopod worms. In the Notostraca also the body is 

 elongated, and composed of numerous somites, but its anterior 

 portion is covered by a broad arched carapace (Fig. 16). In the 



