411] ANOPLOCEPHALIDJE—DOUTHITT 61 



swampy region in which the gophers can live only along the margins 

 of the low river terraces which cross the flat. With a single exception, 

 every adult gopher examined was infected, this locality and another 200 

 meters away which was similar yielding five species of Anoplocephalid 

 cestodes of three genera. Twenty-six specimens, representing three spe- 

 cies, were taken from one host. When one considers that the gopher 

 never wanders more than a few feet from the mouth of his burrow 

 except during the mating season this fact becomes all the more signifi- 

 cant. The conclusion is forced upon the student that there is some 

 connection with the nature of the soil that determines the infection; 

 it seems most probable that the intermediate hosts are plant-feeding 

 insects that live only in fertile soil preferring wet lowlands. 



Since this rule holds true for six species of four genera of the 

 Anoplocephalidae it seems probable that it will hold true for the family 

 generally; that there is something associated with fertile soils and 

 swampy places that is necessary for the continued existence of these 

 parasites ; that if cattle and sheep could be confined to sandhill pastures 

 (which assuredly would not be practical), they would not become in- 

 fected with Thysanosoma and Moniezia. This rule is at least worth 

 trying out by other workers who are giving attention to the life-histories 

 of these cestodes. The camel cricket (Ceuthophilus) has been found to 

 abound in the tunnels of the pocket gopher in localities where these 

 cestodes occur and to be absent from localities where the cestodes do 

 not occur. However all attempts to infect these animals have resulted 

 in failures. It is my intention to continue these experiments both with 

 these animals and others whenever opportunity offers. 



The following table shows the infections found in adult gophers. 

 All gophers that were less than 8 months old, even tho fully grown were 

 without exception uninfected. The separation of the various species 

 of Hymenolepis which were found was rather hastily done and only 

 approximate correctness was aimed at. The species of Cittotaenia from 

 Brainerd, Minnesota, was unfortunately immature and could not be 

 worked out. It is not C. praecocquis described by Stiles (1896) from 

 the same host-species. The examinations were all made by me, with the 

 exception of those from Nebraska for which I have to thank Dr. John 

 E. Gutberlet. 



