114 ZOOLOGY 



budding of the embryos. In the Cestoda, the group in which 

 parasitism has left the deepest mark, the whole alimentary system 

 has disappeared leaving no trace, and the food is absorbed 

 through the skin. In both groups the sense organs, for which 

 they can have but little use, are very poorly or not at all 

 developed. 



There can be little doubt that the Cestoda and Tebma- 

 TODA are connected, or that the former have become more 

 modified and departed farther from their common ancestor, 

 than the latter. Lang's researches lead him to look for the 

 ancestors of the Tkematoda amongst the Tttebellaeia, and 

 especially amongst the Triclades, which group contains some 

 species not easily distinguished from the ectoparasitic Trema- 

 todes, but for their ciliation. 



