244 ILLINOIS BIOLOGICAL MONOGRAPHS [244 



times a large inflation (Fig. 38). Since this is not always present it 

 must be due to the contraction of the heavy longitudinal muscles of the 

 upper part of the neck. The neck itself is broad, thin and long, being 

 0.85-1.0 mm. broad by 4-8 mm. long. 



The first proglottids are short, their breadth equalling several times 

 the length. As the proglottids become older the shape changes from 

 the rectangular to nearly quadrate or quadrate. Proglottids ranging in 

 age from nearly mature to ripe are usually longer than broad. Those 

 proglottids which show the beginnings of the cirrus-pouch and vagina 

 measure 0.5 mm. long by 1.0 mm. broad while those in which the anlagen 

 of the testes are appearing measure 0.680 mm. long by 0.850 mm. broad. 

 Both length and breadth increase greatly as the segments near maturity. 

 A few nearly ripe proglottids are broader than long, measuring 3.25 

 mm. long by 4.25 mm. broad. The longest proglottid found measured 

 8 mm. long by 2.75 mm. broad while many proglottids measure 3-5 mm. 

 long by 2-3 mm. broad. The surface of the body is somewhat wrinkled, 

 due perhaps to having lain twisted for a long time in the alcohol. There 

 seem normally to be no furrows either longitudinal or transverse. Pro- 

 glottid limits are not well defined in young proglottids but are well 

 defined in the older ones. 



The genital aperture is marginal, irregularly alternating. Fre- 

 quently the aperture occurs on the same side in several successive pro- 

 glottids but always in greater numbers on the left side. The greatest 

 number of genital apertures found occurring successively on the left 

 side was ten. No papilla marks the genital aperture. Indeed in many 

 proglottids the muscles are so contracted about the genital aperture as 

 to cause a deep depression (Fig. 100). In such cases it is noteworthy 

 that the cirrus and vagina open to the exterior separately. In many 

 cases it is doubtful if a true genital sinus exists. If present it is ex- 

 tremely shallow. The arrangement of the sexual organs agrees in 

 general with that of other Proteocephalids. 



The cirrus-pouch (Figs. 97, 98) is short and broad, and is broadest 

 at the distal end. It is either straight or curved, depending upon the 

 state of contraction of the proglottid and of the muscles in the region 

 of the genital aperture. When the region of the genital aperture is 

 depressed the cirrus-pouch is usually somewhat bent (Fig. 100). Its 

 length is 0.64-0.75 mm. and its breadth 0.24-0.26 mm. The ratio of its 

 length to the breadth of the proglottid is 1:3 or 1:5. The cirrus (Figs. 

 97, 98) when protruded is thick, short, straight and heavily muscled. 

 It is continuous with the ductus ejaculatorius which forms no, or at 

 least few, coils within the cirrus-pouch. The drawings (Figs. 97, 98) 

 show only a slight twist or turn in this part of the ductus. This descrip- 



