40 ILLINOIS BIOLOGICAL MONOGRAPHS [390 



from the pore, and on the pore side to 3/*. The ventral duct at the 

 ends of the proglottids is 40 to 50/* in diameter ; it narrows in the middle 

 to 30 to 35fi on the side away from the pore, and on the pore side to 

 3 by 10ft. The transverse commissure of the ventral duct is a straight 

 tube 25 to 40ft in diameter. In three individuals the dorsal longitu- 

 dinal duct is connected with the transverse commissure in very many 

 cases (Fig. 40). In the present species these connections are always 

 on the same side of the strobila, judged to be the right side, tho since 

 the specimens are in longitudinal sections this could not be determined 

 finally. 



In the anterior aporose portion of the proglottid the transverse 

 commissure becomes divided and with the aid of the main duct sur- 

 rounds an "island" of medullary parenchyma which varies from 60 

 to 200ft long and may have its long axis either longitudinal or trans- 

 verse. From this region but varying considerably in point of origin 

 a large branch duct extends distad and mediad into the proglottid. 

 This duct persists after the uterus is fully formed, projecting free into 

 its cavity and invested by its walls. Frequently a similar duct will 

 extend forward from the transverse commissure in the lower pore corner 

 of the proglottid. 



There appears to be no doubt but that this cestode is most nearly 

 allied to the genus Schizotaenia. Yet it shows very clearly that it is 

 related to the genus Anoplocephala and appears to be transitional be- 

 tween the two. Aside from the close general resemblances between the 

 two genera the following characters show its close relationship to the 

 known representatives of the genus Anoplocephala. 



1. The testes are mainly on the side away from the pore. 



2. The vitelline gland is of the type found in Anoplocephala, and 

 shows no suggestion of the type occurring in most other known Schizo- 

 taenia. 



3. The uterus develops by regular anterior and posterior out- 

 pocketing. 



4. The cirrus pouch is unusually large. 



THE GENUS SCHIZOTAENIA 



Deiner (1912) has published an account of the anatomy of Taenia 

 magna Murie 1870, under the name Anoplocephala latissima, the specific 

 name "magna" being dropped because preoccupied by A. magna Abild- 

 gaard 1789. The account is very thoro and bears all the marks of being 

 strictly dependable. A consideration of the anatomical features leaves 

 no doubt whatever in my mind but that this cestode is a true repre- 



