Habits and structure of Cotylaspis insignis Lerny. 295 
In trematodes generally where a cirrus sack exists the seminal 
vesicle is situated within it, and not externally to it as here. At 
the point where the duct enters the vesicle in C. insignis (Fig. 37) 
I constantly found in its cavity two or more small concretionary 
bodies. They are large and distinct, and consist of a dark stainable 
interior surrounded by an outer translucent non-stainable portion. 
One of them from a section is shown in Fig. 37. I have not been 
able to account for them, and do not find mention of anything 
similar in other trematodes. They are not to be found elsewhere 
in the sexual apparatus. The seminal vesicle lies almost wholly 
external to the cirrus sack, which is unusual in trematodes where 
the cirrus sack is present. Its wall is epithelial and slightly 
muscular. The cirrus sack measures 0.40 mm by 0.20 mm, its wall 
is very distinct and strongly muscular, the fibres, running in two 
directions. There is a small continuation of the seminal vesicle 
inside the cirrus sack, followed by a dilated portion somewhat curved 
in its course, which I take to be the “pars prostatica”. Its wall is 
composed of rather large nucleated epithelium cells within, and 
strong masses of longitudinal and circular muscle. The cirrus sack 
contains numbers of cells which may be prostate gland cells, but 
I have not been able to recognize that they discharged into the 
pars prostatica, though very probably they do. The outer part of 
the passage is sub-divided into two parts a broader deeper portion 
spread out over the top of the pars prostatica and a more slender 
outer part, ejaculatory duct, connecting with the genital opening. 
The deeper portion is lined with epithelium cells like those of the 
pars prostatica, the outer part is lined with a cuticle continuous with 
that of the outer surface through the genital pore. There are 
indications of a direct transition from epithelium into cuticle here 
as in the gullet and excretory bladder. The structure of Aspidogaster 
conchicola (STAFFORD, 1896) includes a very highly complex system 
of coeca in connection with the ejaculatory duct. This feature is 
not present in C. insignis, though the way in which it flattens down 
over the prostate part is somewhat similar. It does not appear 
(Looss, 1902) that the complex coecal apparatus is present in 
Lophotaspis valle. I infer from the presence of the fold in the center 
of the ejaculatory duct that the outer portion is eversible but have 
seen no evidence of its eversion. 
À 
Zool. Jahrb. XXI. Abt. f. Anat. 15 
