75] PROTEOCEPHALIDAE — LA RUE 75 



pore is not marked by a papilla. The common genital sinus is marginal, 

 irregularly alternating, and situated near or slightly anterior to the 

 middle of the segment. 



Kraeraer worked out in considerable detail the structure of the 

 cuticula, the musculature, the parenchyma, the nervous system, the ex- 

 cretory system, and the histological structure of the various internal 

 organs. In the main the writer does not discuss these points, but since 

 some of Kraemer's conclusions are incorrect the errors are indicated 

 when possible. 



In preparations studied by the writer the testes number 30-35 and 

 they measure 0.037 by 0.053 mm. Kraemer recorded 27-30 testes with 

 a diameter of 0.057 mm. The testes (Figs. 57, 178) lie in a single layer 

 in the field bounded by the ovary, the anterior margin of the proglottid 

 and the vitellaria. The cirrus-pouch is 0.196-0.255 mm. long in fully ma- 

 ture proglottids, where its ratio to the proglottid breadth is 1 :3-l :2. In 

 fully ripe proglottids it is more or less concealed by the uterine pouches. 

 In a few ripe proglottids in which it was not contracted the cirrus-pouch 

 measured 0,370-0.420 mm. in length. Apparently in this species the 

 cirrus-pouch becomes larger after sexual maturity is attained. The 

 cirrus-pouch is slender. Its inner end is slightly curved upward toward 

 the dorsal surface where it is attached to the walls of the dermo-muscular 

 sac by strong muscle fibers. This inner end (Figs. 57, 178) is usually 

 somewhat swollen making a little vesicle. With this vesicle one or two 

 sinuous curves of the ductus ejaculatorius may be seen. Adjacent to 

 the vesicle is the constricted region of the cirrus-pouch. Here even in 

 toto preparations strong circular muscle fibers may be seen. In this re- 

 gion the ductus passes over into the straight slender cirrus* Just beyond 

 this constricted region the cirrus-pouch again dilates a little and here 

 the circular muscle fibers are not prominently developed. From a cir- 

 rus-pouch so constricted the cirrus itself is usually protruded. The 

 length of the incompletely protruded cirrus is about 0.026 mm. Krae- 

 mer states that the cirrus protrudes 2-3 mm. This must be an error, 

 probably typographical, for a cirrus as long as 2-3 mm. would require 

 first a very large cirrus-pouch and, second, many coils of vas deferens 

 within the pouch. Kraemer's drawings and data are not convincing 

 that this is the case. His figure (Fig. 178) shows a protruded cirrus 

 probably not over 0.3 mm. in length. The vas deferens forms a mass of 

 coils at the inner end of the cirrus-pouch. In mature proglottids this 

 knot lies in the mid-field, even reaching past the middle. 



Kraemer undoubtedly made some errors in his description of the 

 cirrus of this species. Benedict (1900) pointed out these errors thus: 



