.-.5G 



From (his iiihic it will ho not iced that (> ditTcrent 

 tape\v(>riiis hinc hccii recorded from pigeons, - from 

 liirkcvs, I 1 Inmi chickens, 'J from Swaus, 7 from geese, 

 K! from ducks, and I from ostriches; 1 form has been 

 recorded as common to pigwins, chickens, and ducks; 

 ."i foi'ms as common to ducks aud geese; 1 form as com- 

 mon (o 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, aud that 

 the specific determinations of tlie parasites were cor 

 rect. A comparison of the original types would, how 

 ever, undoubtedly show that both of these sujipositions 

 are incorrect, for many of the species are very poorly 

 described, and have been established upon yery limited 

 material. 



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

 worthless; some of the species i-est upon very woak characters 

 ancl must undoubtedly fall, while the synonymy and proper 

 names of the s'l-oiip need thorough revision. It would be haz- 

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

 In fact, I do not believei this should be done unless the worker 

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

 him. 



l.tFlO HK^TORY .\Nn SOUROK OF INFECTION. 



Fortunately tlie 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 specific 

 diagnosis will show the source of infection (interme 

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

 no grounds for believing that poultry can become in 

 fected with tapeworms directly fix>m the eggs con- 

 tained in the droppings. 



