407] ANOPLOCEPHALIDsE—DOUTHITT 57 



in form and size, or much smaller (the pouch is larger in the other 

 genera). 



3. The testes are mainly anterior. 



4. In species concerning which information is available, the ovi- 

 duct and ovary are related to each other as in Andrya, and not as in 

 Schizotaenia. 



The following points argue for relationship rather to Schizotaenia- 

 like forms, however. 



1. The cirrus is sometimes spiny. 



2. The genital pores are sometimes regularly alternate. 



3. The uterus, at least in anlage, is confined to the median field. 



4. The dorsal excretory ducts are often dorsomedian, as in rela- 

 tives of Schizotaenia. 



5. The testes seem to be confined to the median field, as in Schizo- 

 taenia; in some species of Schizotaenia, also, the testes are anterior. 



I am inclined to consider the aguments for closest relationship to 

 the genus Andrya as the most important, and to attribute the resem- 

 blances to Schizotaenia to parallel evolution. 



The relationships of the genus Triplotaenia are problematical and 

 will probably always remain uncertain. The possession of two sets of 

 reproductive organs suggests relationship to Cittotaenia or Moniezia. 

 The following points argue for relationship to Schizotaenia. 



1. The uterus, in anlage, is confined to the median field. 



2. The horns of the pyriform body are long and filamentous. 



3. The vagina is inconspicuous and apparently ephemeral. 

 These points argue for little more than general relationship however 

 and all of them might easily be accidental. 



The following points argue that Thysanosoma is most nearly related 

 to the higher representatives of the Anoplocephalinae and is descended 

 from forms like Moniezia and Schizotaenia. 



1. There are sometimes two sets of reproductive organs in Thy- 

 sanomosa. 



2. The genital ducts sometimes cross the excretory ducts ventrally 

 in Schizotaenia. 



3. The genital organs are placed far laterad, in Thysanosoma. 



4. The vaginal pore may be dorsal, or anterior to the cirrus pouch, 

 in Thysanosoma. 



5. Accessory transverse commissures of the excretory ducts are 

 present in species of both Schizotaenia and Thysanosoma. 



These arguments however are at best inconclusive. The most that 

 can be said is that Thysanosoma seems to be related to the higher 

 Anoplocephalinae . 



