236 48 



regarded some parts of the indusium or of the sac, filled with opaque corns, (often 

 almost empty) as the contractile vesicle; Plate and Weber state correctly that 

 there is no contractile vesicle; the two canals debouch directly on both sides of the 

 genital opening. Special setæ round the two openings (Plate, Weber) 1 have not 

 been able to see. As in the female so also in the male on both sides we really 

 find two canals; the straighter one carries the vibratile tags to a number of four, 

 the other is secretoz-y and exhibits numerous slings; how these two canals are con- 

 nected with each other, I have not been able to elucidate. 



The testis is large, pyriform, containing numerous spermatozoa of two different 

 kinds, the acute staff-formed ones are here always lying in the place, where the testis 

 passes into the ductus seminalis; this is long, in its interior covered with cilia and 

 provided with two prostata glands of very different size. The ductus seminalis is 

 further transversely striped with fine and numerous muscle bands. This has also 

 been seen by Weber who further states, that it is only a thick cuticular sheath, 

 containing in its interior the true penis, "cordon fin, délicat et très pointu" (1888 

 p. 4.Ö). I have always been quite unable to see anything of that. The ductus semi- 

 nalis opens dorsall}' at some distance from the toes; more than once I have seen 

 the evaginated ductus seminalis surrounded by a crown of cilia turned out; I am 

 inclined to think that, in Hydatina senla just as in most of the Xotoinmatidce there 

 is no real penis, but that it is the ductus seminalis which, turned inside out, is used 

 as such (Tab. X, fig. 3). There are two very large foot glands. 



The muscle system is highly developed; in the figs. 1 — 2, Tab. ^'III 1 have 

 tried to give a sketch of it; compared with the figures of Martini (female) it will 

 be seen, that there is great accordance between his and my drawings; but on the 

 other hand also some very conspicuous differences. As the muscle system has been 

 studied only upon living animals 1 do not think it is correct to go into details, in 

 as much as I hope that a more elaborate study of the anatomy of the male will 

 appear later on. 1 only wish to remark that, also in the male, the muscles of the 

 forepart and those of the hindpart overlap each other in the middle line of the body. 

 When the animal has been hing under pressure for some hours and is almost 

 dying, a moment arrives, when some parts of the muscles are extremelj' conspicuous. 

 This is especially the case with the transversal muscles. In Fig. 1, Tab. IX I have tried 

 by means of the camera to give as thorough a drawing of the transversal muscles as 

 possible. The figure shows the peculiar manner in which these transversal muscle 

 bands are connected with each other and are provided with large nuclei, situated 

 in expansions of the bands. When comparing the figure with those of Zelincka of 

 Discopns I have now and then thought that I had to do with some parts of the 

 sympathie nerve system, which has only been observed by him, but continuous 

 examinations have convinced me that this was not the case. 



Above the testis there are from one to three hyaline sacs containing a number 

 of opaque corns of different size and numbers; these sacs are in accordance with 

 those which are almost always found in the males and ver}' often in the females. 



