18 ILLINOIS BIOLOGICAL MONOGRAPHS [368 



Anoplocephala wimerosa has a length of 10 mm. and a breadth of 

 1.5 to 2.25 mm., and contains 10 to 28 proglottids. The proglottids are 

 much broader than long, except the distal segments, which rarely be- 

 come as long as broad. The head is 0.7 to 0.88 mm. in diameter, is 

 cuboid in form, and is quite distinct from the strobila. The suckers 

 are 0.4 mm. in diameter, are prominent, and open diagonally forward. 



As would be expected in so short a strobila, each proglottid shows 

 a distinct advance in development over the one before. The genital 

 organs are fairly well formed in the first proglottid. The receptaculum 

 seminis begins to fill with spermatozoa in the fifth. By the fifteenth 

 the testes have practically disappeared, and the receptaculum, vesicula, 

 and cirrus pouch are enormously distended with spermatozoa. A few 

 remnants of the testes persist until the eighteenth. The ovary develops 

 to its full size in the eighth or ninth proglottid and begins to discharge 

 eggs into the uterus. In the next proglottid this process is completed 

 and the ovary disappears. 



The testes, which are frequently as much as 90/i long, are irregular 

 in shape. They occur on the side away from the pore and reach laterad 

 to beyond the excretory ducts. The number, in six proglottids counted, 

 ranged from 31 to 42. Not more than two testes can lie in a row in 

 the axis of the strobila. The cirrus pouch is enormous. In a mature 

 proglottid it is 520/1 long and at its inner end extends thru the entire 

 length of the proglottid. Its median end is occupied by a portion of the 

 vesicula seminalis, 190/x long. The portion of the vesicula outside the 

 pouch has a length in mature proglottids of 100/x. and is two-thirds as 

 wide. In older proglottids the entire vesicula becomes much larger. 

 The cirrus pouch lies of necessity almost entirely mediad of the excre- 

 tory ducts. 



The genital pores are dextral. When undisturbed, the cloaca is 

 200/i deep. When the proglottid enters the period of sexual activity, 

 it turns inside out. In the third or fourth segment succeeding, it is 

 again drawn back. In this feature and in the enormous size of the 

 cloaca and the cirrus pouch this cestode recalls Schizotaenia, especially 

 S. anoplocephaloides, described in this paper. The unexpanded portion 

 of the vagina is about 300/i. long. Throughout its entire length it lies 

 ventrad of the cirrus pouch, as does also the vaginal pore. No indica- 

 tion of glandular structure in its walls was observed. The receptacu- 

 lum seminis is 300/i. long in mature proglottids and at its median end 

 extends from the anterior to the posterior border of the proglottid. 

 Latterly it narrows regularly and evenly. In succeeding segments it 

 becomes enormously distended. 



