10 ILLINOIS BIOLOGICAL MONOGRAPHS [360 



The uterus is a typical reticulum in its early stages. It lies entirely 

 anterior to and to the left of the ovary, being never ventrad of it. To 

 the left of the ovary it reaches the transverse commissure posteriorly. 

 On either side it crosses the ventral excretory ducts ventrally. Devel 

 opment from this stage is as in A. primordialis. 



The excretory ducts are dorsal and ventral in position in the head 

 region ; but the dorsal duct very early moves to a position laterad of 

 the ventral, which it retains. The ventral duct is four times the diame- 

 ter of the dorsal; the transverse commissure is very small. The ventral 

 duct diverges from the central axis as it passes distad until near the 

 distal end of the proglottid where it turns almost directly mediad to 

 regain its position. The dorsal duct has a somewhat similar course but 

 not so pronounced. 



This cestode it will be seen is rather closely related to Andrya 

 primordialis. Many of the differences in the two accounts are due 

 probably to differences in the state of contraction in the material. 



Andrya macrocephala sp. nov. 



[Figures 9-13] 



Fifteen specimens of this species were taken from pocket gophers 

 (Geomys bursarius) living in swampy river bottom land at Brainerd, 

 Minnesota, and one from a gopher living in low, heavy, black soil at 

 Thief River Falls, Minnesota. Apparently they are entirely absent 

 from sandhill regions if not from all uplands. For distribution and 

 frequency see the table on page 62. 



By far the most conspicuous anatomical feature of this cestode is 

 the enormous development of the ventral excretory ducts and commis- 

 sures. In the scolex anterior to the distal end of the suckers, the four 

 ducts have a winding course, the diameter of each varying generally 

 between 18 and 32//.. Distad of the suckers the ducts have a straight 

 course, are approximately 15//. in diameter, and are arranged as a dorsal 

 and a ventral pair. Near the distal end of the scolex the dorsal duct 

 begins to move laterad and soon comes to lie directly laterad of the 

 ventral. The diameter of the dorsal duct throughout the strobila is 

 about 18//.. The ventral ducts increase considerably in size as they pass 

 distad. As the proglottids approach sexual maturity this increase be- 

 comes much more rapid and the transverse commissures appear and 

 develop rapidly. In a sexually mature proglottid the ventral aporose 

 duct near the middle of the proglottid is 80//, in transverse diameter; 

 at either end it is 145//. in diameter. On the pore side the transverse 

 diameter is 125//. in the center; at either end, 150// or more. The 



