397] PSEUDOPHYLLIDEA FROM FISHES—COOPER 109 



commonest measurement. The vas deferens, filled with sperms, forms a com- 

 pact mass of coils about 0.18 by 0.10mm. in size, lying irregularly to the right 

 or left of the uterine duct or sUghtly behind the sac and unmediately alongside 

 the cirrus-sac, as shown in Fig. 71. The ductus ejaculatorius portion of the 

 vas deferens within the cirrus-sac, that is, that part occupying the lowermost 

 one-third of the latter, has a diameter of from 4 to 6ju. The middle stretch of 

 the duct often expands to 13^, while the distal part, the cirrus proper, has a 

 maximum length of 65m "with a width of 14^. Matz gave the dimensions of the 

 organ (? the cirrus-sac) as 100 by 50^. The cuticula lining the cirrus is pseudo- 

 iliated on its inner (functionally outer) surface, somewhat as is that on the 

 external surface of the worm. The cirrus-sac is located at right angles to the 

 dorsal surface (Fig. 95) and extends only a short distance into the medulla, as 

 compared to other species. It is ovoid in shape, with the narrower end towards 

 the cloaca, and from 115 to 120/i in length by from 75 to 80m in diameter. Its 

 wall is composed of an inner thick layer of circular muscles and a very thin 

 outer layer, the fibres of which are directed somewhat obUquely, the whole 

 being 8m in thickness. As pointed out by Lonnberg and showTi in figure 95, 

 the organ is pecuHar in that its wall is coated both externally and internally 

 with a thick layer of nuclei which are doubtless mostly myoblastic in their 

 nature. An aggregation of nuclei at the lower pole of the sac, surrounding 

 the vas deferens and continuous with the layer of nuclei on the outside of the 

 pouch, are too numerous to be considered as myoblastic nuclei only. They do 

 not seem to be mentioned either by Lonnberg or Matz. Their arrangement 

 would indicate that they are possibly prostatic in their nature, the whole struc- 

 ture having the appearance of a gland. Retractor muscles of the cirrus proper 

 are scarce. This fact, taken in conjunction with the further fact that the 

 wall of the sac is quite thick and powerful, and that Lonnberg saw only a short 

 thick cirrus when protruded, would lend support to the view that the latter 

 is quite small and not very important from a functional standpoint. Concern- 

 ing copulation in tliis species Lonnberg said: "Es ist daher wahrscheinlich, 

 dass die normale Befruchtung so vor sich geht, dass das Sperma in den Sinus 

 genitahs hinausgepresst wird, und davon entweder passiv durch die Kontrak- 

 tion der Sinus genitalis oder aktiv durch eigene Bewegung in die Vagina gelangt. 

 Sowohl die eine als die andere Weise scheint recht mogUch zu sein, well die 

 Miindung der Vagina ganz neben derjenigen des Penis gelegen ist. " 



The vagina opens into the ductus hermaphroditicus close behind the cirrus. 

 From there it proceeds close along the cirrus-sac to its lower end, and then 

 turns back to pass over the ovarian isthmus and into the generative space. Its 

 diameter is 13m, while its wall is composed of a cuticula 5m in thickness and a 

 thin layer of circular muscles. Its cuticula is retained until the point of union 

 with the oviduct is reached, where the lumen narrows down suddenly to one- 

 half the former diameter (Fig. 105). The ovary with a width of 0.35mm. and 

 a length of 0.15mni., is somewhat irregularly "biscuit-shaped" (Fig. 71) and 

 situated close to the posterior border of the segment or protruding slightly 

 into the segment behind. It is composed of short tubular lobules of varying 



