3471 PSEUDOPHYLLIDEA FROM FISHES— COOPER 59 



meter, are accommodated in the somewhat confined space dorsal and anterior 

 to the cirrus-sac, extending to the ovary ahead (Fig. 93). Whereas Kraemer 

 gave the diameter of the duct as 0.133mm. or about eight times as large as just 

 before it enters the cirrus-sac, it is only 45^ at the most in this species. Fur- 

 thermore, it is not enlarged to form a seminal vesicle close to the cirrus-sac, 

 as shown in Kraemer's figures 6 and 13, but gradually diminishes in size until 

 as it pierces the wall of the latter its diameter is only 10^. Nor is the whole 

 vas deferens enclosed in a connective tissue sac, such as described by Kraemer. 

 Within the pouch it enlarges considerably to form a thin-walled inner seminal 

 vesicle, situated for the most part near the proximal end of the former but often 

 lying alongside the cirrus proper. This portion of the duct may attain a 

 diameter of 30/x even when empty. Then follows the cirrus proper which is 

 sharply separated from the seminal vesicle ; as a matter of fact it actually pro- 

 trudes backward into the latter with a diameter of 10^ and for a distance of 

 from 15 to 25/x. The extruded cirrus has a maximum length of 200/i, diameter 

 at the base of 120^1, and at the tip of about 40^. The thick cuticula covering 

 the organ is decidedly roughened or irregularly "cleft," especially towards the 

 tip, but not provided with spines of any kind. Incidentally, the protrusion of 

 the cirrus on account of its size, results in the eversion of almost the whole of 

 the contents of the sac. The length of the cirrus within the sac is at least 185^, 

 — it is usually bent once in its proximal portion— while its diameter varies 

 considerably. The layer of parenchymatous and myoblastic nuclei surround- 

 ing the cirrus within the sac is about 10^ in thickness as compared with 5/i in 

 C truncakis. In sections of the extended cirrus most of these nuclei appear in 

 the tip of the organ surrounding a good deal of the cuticula which still remains 

 invaginated; but they are in all probability myoblastic as are others farther 

 back along the course of the retractor fibres. In frontal sections the cirrus-sac 

 is circular in outline (Fig. 93), its maximum diameter being 175m, while in 

 transverse and longitudinal sections it is oval in shape and the diameter (length 

 of the organ) ranges from 200 to 230^. The smaller end is directed ventrally. 

 Its waU is comparatively thin, ill defined, and composed of a som.ewhat loose 

 network of muscular fibres running irregularly obhquely in all directions, so 

 that sections cut in any plane show them almost circularly arranged. Owing 

 to this fact and to the further fact that its innermost fibres are not easily dif- 

 ferentiated from the retractors of the cirrus proper which bulk largely in the 

 contents of the sac, the wall is fairly difficult to locate with emission of the cir- 

 lus. The sac is furthermore not provided with any retractors connecting it 

 with the dorsal body-wall as described by Kraemer for C. truncatiis. Formmg 

 a sort of gland closely applied to that part of the cirrus-sac within the medulla 

 there is to be seen, even in toto preparations, a comparatively large mass of 

 large darkly pigmented polygonal cells (Fig. 93). In frontal sections they Ue 

 on each side of the sac but do not extend much beyond its anterior and poster- 

 ior edges, the whole structure being thus shaped somewhat like a saddle. Each 

 cell is elongate in shape provided with a well-defined wall, prominent tho not 

 especially large nucleus, and very granular and highly pigmented cytoplasm. 



