355] PSEUDOPHYLLIDEA FROM FISHES— COOPER 67 



from proglottis to proglottis. As a matter of fact, they are confined to the 

 areas between the two pairs of the four main longitudinal excretory trunks 

 mentioned above. They are usually almost spherical in shape with maximum 

 diameters of 80 to 100/n. Transverse and sagittal sections show that, owing to 

 the large size of the median reproductive organs, especially the large uterus, 

 and their consequent inability to expand laterally, they are arranged in two 

 pseudostrata which occupy the whole of the dorsoventral diameter of the medul- 

 la of the regions in question. These two tiers are, however, not nearly as 

 extensive as in B. pachycephdus Linstow (1904:308, Fig. 26). The vas deferens 

 is in the form of a narrow mass of coils, situated immediately anterodorsal to 

 the cirrus-sac or slightly to one side, depending on the amoimt of distension 

 and consequent approximation of the uterus of the same proglottis to that of 

 the proglottis ahead. It also extends to the dorsal wall of the medulla; and 

 its diameter is about 30^. Just within the cirrus-sac the vas deferens is sur- 

 rounded for a short distance by radiating gland-like ceUs, reminding one of 

 those outside of the pouch in C. americanus. But there are no such cells out- 

 side of the cirrus-sac as described for B. nylandicus by Schneider. Then it 

 gradually diminishes from a diameter of 35)u in the ejaculatory region, which 

 immediately follows, or perhaps includes the glandular region, to about 20/a 

 at the middle of the sac. From this point it enlarges quickly and takes on the 

 cuticula and a series of circular muscular fibres to form the cirrus proper which 

 in the distal portion of the pouch may attain a diameter of SOju. The extended 

 cirrus has a maximum length of about 60/x and diameter of 85m. The cirrus-sac 

 is oval in shape, the smaller end being outward and the major axis at right 

 angles to the surface. Its depth is 0.25mm. while its diameter is 0.17mm. 

 As in C. americanus its muscular walls are only weakly developed and hence 

 not very distinctly separated from the parenchymatous tissue within and with- 

 out. Apart from the duct the contents of the pouch consists of numerous 

 parenchymatous cells and retractor muscles, the whole forming a quite compact 

 structure. 



Just within the medulla the vagina turns backward and continues ventrally 

 and posteriorly with a few coils toward the ovarian isthmus. Whereas its 

 diameter is 30)u near its opening, half way along its course this is reduced to 

 10/ii and enlarged again to 40 to 60/i to form the seminal receptacle. Close 

 behind and somewhat dorsal to the isthmus it again becomes sharply restricted 

 to 10/i to form the spermiduct. Its whole course is quite as described for B. 

 nylandicus] but in the latter there is evidently no enlargement to form a seminal 

 receptacle or it was overlooked by Schneider, as indicated in his statement: 

 " Sie passiert gleichfalls auf dem kiirzesten Wege die Subcuticularschicht imd 

 die Muskelschichten, biegt dann in stumpfem Winkel nach hinten lun und 

 zieht, immer enger werdend, gegen den Ovidukt hin. In der Nahe des Eileiters 

 wird sie so eng imd diiniiwandig, dass die EinmundungssteUe nicht genau 

 festgestellt werden konnte." The ovary is like that of B. nylandicus in 

 that it is crescentic in shape, the tubulolobular wings extending to the dorsal 

 musculature and surroimding the uterine coils. It is, furthermore, comparable 



