453] PSEUDOPHYLLIDEA FROM FISHES— COOPER 165 



thus appearing as a low cone or crater. No sphincters control the openings 

 of either of these sinuses ])ut the cuticula of the floor of the larger or outer is 

 modified to form coarse, low, rounded and closely set papillae which are evi- 

 dently of special importance during copulation. These papillae would evidently 

 serve to temporarily fasten the structure into the primary sinus of another 

 proglottis, when it is possibly everted with the cirrus. Copulation was not 

 observed in this species during life, nor were any cases of protruded cirrus met 

 with in the material at hand. 



All of the proximal portions of the reproductive organs, excepting the 

 vitelline follicles, are located in the medullary parenchyma, although the much 

 distended uterus-sac, originally in the latter, extends almost to the cuticula on 

 both the dorsal and ventral surfaces. Figure 75 shows their arrangement in 

 toto. 



The testes are closely arranged in the medullary parenchyma in two lateral 

 fields, each bounded laterally by the junctions of the dorsal and ventral layers 

 of longitudinal muscles and medially by the other reproductive organs (except- 

 ing the vitelline glands) vrhich occupy in the quadrate proglottides about the 

 middle one-third of the transverse diameter of the strobila and are contiguous 

 from joint to joint. In the quite mature elongated proglottides the testes are 

 ellipsoidal in shape, averaging 0.125mm. in length by 0.040 in diameter, the 

 cross-section being usually about circular in outline. In younger joints and in 

 all those of much contracted strobilas the testes are nearly spherical in shape, 

 measuring about 60/i in diameter, or often slightly longer than broad. They 

 are arranged in a single layer in the medulla, the whole dorsoventral diameter 

 of which they occupy, and are continuous from proglottis to proglottis. From 

 2 to 4 appear in each lateral field in transverse sections, from 5 to 7 are seen in 

 sagittal sections between the posterior borders of consecutive proglottides, 

 while, so far as could be determined from frontal series directly, the number is 

 from 20 to 25. Thus each proglottis contains from 40 to 50 testes. 



The vas deferens forms a wedge-shaped mass of closely arranged coils, 

 extending forv\'ard immediately ahead of the cirrus-pouch and alongside the 

 uterus-sac for about two-thirds of its length (Fig. 75) . In proglottides in which 

 the latter is yet comparatively small the vas deferens may pass forward as 

 far as its anterior end. In either case it forms with the cirrus-pouch a mass 

 which alternates from right to left with the uterus-sac. WTien distended with 

 sperms the duct averages about 30/i in diameter; but just before it enters the 

 cirrus-sac anterodorsally it narrows down to 5^. Immediately within the wall 

 of the latter it often enlarges again to form a thin-walled functional vesicula 

 seminalis, or perhaps more correctly ductus ejaculatorius, from 13 to 23/i in 

 diameter. After one or two short turns it diminishes again to about 8/x and 

 then passes on as the cirrus proper. While the proximal portions of the duct 

 do not pass in any definite direction, the latter is situated for most of its length 

 in the longitudinal axis of the pouch. It is about 0.10mm. in length and about 

 20 to 25)u in diameter at its middle. It is hned with a cuticula, lO^t thick, which 

 is cleft but not armed with bristles of any kind. 



