34 ILLINOIS BIOLOGICAL MONOGRAPHS [334 



mostly on the pore side of the median line of the proglottid. Beyond 

 the median line they are reduced to a single row which reaches as far 

 as the median axis of the female glands of the proglottids before and 

 behind. On the pore side of the field they are in 2y 2 to 5 rows when 

 viewed from above. They are usually limited to the dorsal part of the 

 proglottid but in one specimen they sometimes extend entirely through 

 the medullary portion. Generally they lie almost entirely posterior to 

 the female glands, but in one specimen they were found sometimes at 

 the same level as the female glands and dorsal to them, and in some 

 proglottids even anterior to them, and therefore if judged by position 

 in the proglottid in front! These different types of distribution were 

 all found in five adjacent proglottids. The number of testes was found 

 to vary from 60 to 70 in one specimen to 110 in another. The number 

 seems to be fairly constant for any given individual. 



As already stated the genital organs alternate regularly from the 

 left to the right side of the strobila. The median line of the female 

 glands in mature proglottids is 600//, from the median line of the pro- 

 glottid ; in 8. americana the distance was 55 to 175/*. The ovary is much 

 smaller than in S. americana, its diameter varying from 650 to 900/i; 

 it never reaches to the median line of the proglottid. Otherwise the 

 ovary is not different from that of S. americana. The ova measure 12 

 to 14/i, in diameter. The vitelline gland shows the peculiar mulberry- 

 like appearance figured by von Janicki for 8. hagmanni. In cross 

 sections of the gland, i. e., longitudinal sections of the proglottid, about 

 25 radiating lobes can be made out. There is no trace of the usual 

 bilobed condition. The shell gland is small and lies directly dorsad 

 of the vitelline gland, having about one-third the diameter of the latter. 

 The uterus in mature proglottids is apparently not so extensive as in 

 8. americana, but statements concerning it must be qualified on account 

 of the poor condition of the material. It does not seem to reach either 

 the anterior or the posterior border of the segment. Otherwise, the 

 description given for 8. americana will apply equally well for the early 

 stages. Unfortunately the later development could not be followed. 



The description given for the excretory system of 8. americana 

 will answer for what seems to be the normal condition here. One 

 individual however offers such radical departures from this type that 

 a detailed description is given here. In the specimen in question the 

 longitudinal portions of both dorsal and ventral ducts are of approxi- 

 mately the same size. In one sectioned portion having five pro- 

 glottids, the large ventral transverse commissure extends laterad to 

 make open connection also with the dorsal duct. Judged by its appear- 

 ance, the commissure would seem to belong to the dorsal rather than 



