556 



From this table it will be noticed that (> ditTerent 

 tapewoi-nus have beeu recorded from pigeons, '1 from 

 iMi-kcys, 1 1 ir(nii chickciis, U from Swans, 7 from geese, 

 K) from dneks, and 1 from ostriches; 1 form has been 

 recorded as common to pigeons, chickens, and ducks; 

 5 forms as common to ducks and geese; 1 form as com- 

 mon to geese and swans; 1 as common to pigeons and 

 ducks, and 1 as common to pigeons and chickens. 

 These statistics are based upon the suppositions that 

 all the parasites mentioned are good species, and that 

 the specific determinations of the parasites were cor- 

 rect. A comparison of the original types would, how- 

 ever, undoubtedly show that both of these su])positions 

 are incorrect, for many of the species are vei*y poorly 

 described, and have been established upon very limited 

 material. 



Many of the specific diagnoses existing- to-day are almost 

 worthless; some of the species rest upon very weak characters 

 and must undoubtedly fall, while the synonymy and proper 

 names of the group need thorough revision. It would be haz- 

 ardous to make any radical changes in the system at present; 

 in fact, I do not believe this should be done unless the worker 

 has a large series of specimens, with types, if possible, before 

 him. 



LIFE HISTORY AND SOURCE OF INFECTION. 



Fortunately the life history of a number of forms is 

 known. So far as yet worked out, the larval stage is 

 in every case a cysticercoid and lives in some inverte- 

 brate (snail, insect, crustacean, or worm). A glance 

 at the above table and the remarks under each s])ecific 

 diagnosis will show the source of infection (intei-me- 

 diate hosts) so far as known or supposed. There are 

 no grounds for believing that poultry can become in- 

 fected with tapeworms directly fi'oni the eggs con 

 tained in the droppings. 



