92 ILLINOIS BIOLOGICAL MONOGRAPHS [442 



EXPLANATION OF PLATE 



Figures 28 and 29. Schizotaenia americana. 



Fig. 28. Mature proglottid, dorsal view; uterus not included. 



Fig. 29. Mature proglottid, showing uterus (dotted), oviduct, and shell gland. 

 Figures 30 to 32. Schizotaenia variabilis. 



Fig. 30. Mature proglottid, dorsal view. After this drawing was completed 

 the study of additional material showed that it is not normal in some respects, 

 namely: (i)-the testes are usually further forward, anterior to the transverse 

 commissure; (2) the accessory ventral commissures were found in only one 

 specimen; (3) the vesicula seminalis is usually not thrown into wide curves as 

 here shown. The uterus may be somewhat more extensive than here shown; the 

 poor condition of the material does not permit exact judgment as to the limits of 

 this structure. 



Fig. 31. Diagram of excretory system of five adjacent proglottids, showing 

 accessory transverse commissures (AVC) and other features. The absence of 

 the main transverse commissure in some cases may be due to the fact that the 

 proglottids are not fully mature. 



Fig. 32. Drawing showing the cloaca only partly everted and the cirrus pouch 

 lying consequently mostly mediad of the excretory ducts. 



