THE TMIOID CESTODES OF NORTH AMERICAN 



BIRDS. 



By Bkayton Howard Ransom, 



Assistant Custodian, Helminthological Collections, U. S. National Museum.. 



INTRODUCTORY REMARKS. 



The tsenioid cestodes are tapeworms characterized priniarily by the 

 presence of four cup-shaped suckers upon the head. They form a 

 natural group, classed by some authorities as a superfamily Ta^n- 

 ioidea, by others as an order Cyclophyllidea. At least 8 families 

 may be recognized, and nearly 70 genera. Over 50 of these genera 

 are represented among the species, about 500 in number, parasitic in 

 birds. About 140 species have been reported from North American 

 birds, and these represent nearly 40 genera. It is with these forms 

 that the present paper is concerned. In order to render clear their 

 relationships, it has been considered desirable to include a synopsis 

 of the entire superfamily to which they belong, giving a diagnosis 

 of every known genus in the group and a key to genera. By means 

 of this key a given specimen may readily be placed in its proper 

 genus. Under each genus is given a list of all species known to 

 occur in North American birds, with references to the more important 

 published descriptions which will be of material assistance in arriv- 

 ing at specific determinations, and in this connection the compendium 

 of parasites arranged according to hosts will also be useful. 



Preceding the synopsis are given a few notes on the collection and 

 preservation of specimens, and descriptions of a number of species 

 which have been specially studied. 



NOTES ON COLLECTION AND PRESERVATION OF SPECIMENS. 



The tapeworms of birds are found usually in the small intestine. 

 The collection of specimens is not particularly difficult. The small 

 intestine is slit from end to end with a pair of scissors of suitable size, 

 and by stripping the slit intestine between the thumb and finger or by 

 scraping the inner surface with the back of a scalpel blade the con- 

 tents are removed into a tall vessel (beaker or glass cylinder) of phys- 

 iological salt solution. In some cases special care is required if the 

 heads of the worms are to be obtained, and it may be necessary to cut 



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