212 ILLINOIS BIOLOGICAL MONOGRAPHS [212 



by 0.75 mm. broad. An end-proglottid with a rounded posterior end 

 may be present, but it is lost with the first ripe proglottids. 



The musculature of the body is weakly developed. This is particu- 

 larly true of the longitudinal muscles which lie between the cortical and 

 medullary layers of the body. In the head the excretory system is 

 made up of coils of small anastomosing vessels which are connected 

 with the two pairs of main lateral vessels extending through the length 

 of the strobila. In the strobila both pairs of lateral vessels lie within 

 the dermo-muscular sheath. The genital canals, cirrus-pouch and 

 vagina, always pass between the dorsal and ventral excretory vessels. 

 The latter are connected with the exterior by numerous branches which 

 discharge on the dorsal or ventral surface more frequently than on the 

 margin of the segment. Regularly situated foramina secundaria do not 

 exist. A transverse excretory commissure uniting the ventral vessels in 

 the posterior part of the proglottid has been observed. The meshes of 

 the parenchyma are coarse, forming numerous large spaces. In mate- 

 rial prepared by ordinary methods this tissue appears to be nothing 

 more than abnormally loose parenchyma. When fresh material is 

 stained with "Sudan III" or is treated with osmic acid these spaces 

 are found to be filled with large fat globules. These tests have likewise 

 been applied by the writer to pieces of 0. lonnbergii with similar results. 

 Fat globules have been found in the tissues of species of Proteocephalus 

 but in this case the fat globules are small. Tests have also been made 

 on Taenia saginata (?), Taenia serrata, and Dipylidium caninum and 

 in each case fats have been found. Tests for fat have not been made 

 on the cestodes of snakes but all the species examined show the loose 

 parenchyma with large spaces which the fat globules once occupied. 



The genital organs (Figs. 103, 104, 105) are typical of the genus. 

 A genital papilla is not present. The genital pore is marginal, irregu- 

 larly alternating, and situated near the end of the anterior fifth of the 

 proglottid. Through the genital pore the small genital atrium is con- 

 nected with the exterior. Into the genital atrium both cirrus and vagina 

 open. The vagina always lies anterior to the cirrus-pouch. The testes 

 (Fig. 105) measure about 0.05-0.06 mm. in diameter. They number 

 about 70-114 and they are situated in two broad fields on either side of 

 a free median zone. They occupy a position dorsal to the uterus. A 

 much coiled vas deferens forms a mass which extends from the cirrus- 

 pouch to the midfield of the proglottid. This mass of coils functions as 

 a vesicula seminalis. Upon entering the cirrus-pouch the vas deferens 

 becomes the ductus ejaculatorius which makes 1-3 coils before passing 

 over into the straight and weakly muscled cirrus. When protruded 

 the cirrus measures 0.2-0.3 mm. in length. It is slender and of almost 



