42 



THE ZOOLOGIST. 



The Turbellarians are all free-living, with the exception of a 

 few marine forms which have taken to parasitism. 



The Trematodes are all parasitic, showing ecto-parasitism as 

 in Polystomium integerrimum, and endo-parasitism as in the Liver 

 Fluke (Distomum hepaticum) . 



The Cestodes, on the other hand, are all endo-parasitic. 



Taking next the phylum Nematohelminthes, we can tabulate 

 it thus : — 



Phylum. 



Family. 



Degree of Parasitism. 



Nematohelminthes. > 



Nematoda. 



Nematomorpha. 



Acanthocephala. 



Free-living and para- 

 sitic forms. 



Also free-living and 

 parasitic forms. 



Solely endo-para- 

 sitic. 



From the above we see that the Nematoda show free living 

 and parasitic forms. 



Such is the case also with the Nematomorpha. But when we 

 come to the family Acanthocephala, it is seen that it has been 

 specially constituted for the justification of a few peculiar genera, 

 of which Echinorhynchus is the best known, and whose larvae 

 live in arthropod and the adult in vertebrate hosts respectively. 



This paper will deal chiefly with the Cestoda, Acanthocephala, 

 and Nematoda which were found in the alimentary canal of 

 some of our common birds. 



An attempt has also been made to show the relation, if any, 

 between the Mallophaga, or lice, found on the birds and the 

 number of parasites found in the intestines. The large table* 

 will show the month, locality, food of bird, and position of para- 

 site when found. The life-history of Cestodes in general might 

 here be stated with advantage. 



Life-history. — Cestodes are exclusively endo-parasitic, i. e., 

 they are found in the tissue or canal of the host upon which they 

 prey. The larval life is lived in the tissues or chambers of 

 invertebrate animals ; while the adult stage of the Cestode is 

 passed in some vertebrate host, with the exception of Archigetes sp. 

 * A single page only of this table is here printed. 



