232 44 



muscles and four pedal muscles, overlapping each other in the middle part of the 

 body; there is no gelatinous enveloping. In different development in the different 

 species I have found a peculiar structure of globules, arranged in something like a 

 very widemeshed net of which I have tried to give an idea in the figure. Length of 

 male 300,«. of female 350 /<. 



With regard to the males of the genus Copeus at our present stage of know- 

 ledge it may be established, that they are relatively highly developed organisms 

 but differing from the females in having no lip, no gelatinous cover, no real tail, 

 no alimentary canal and no contractile vesicle. 



General remarks with regard to the Xotommatidæ. It will be under- 

 stood that our knowledge of the males of the large family of Xotommatidæ is but slight; 

 only a few of the males belonging to the genera: Proales, Diglena. Copeus and Xotommata 

 are well known. From the descriptions of Weber, Rothert, Rousselet and now 

 from my own it seems that the males in outer form rather resemble the females. 

 The size is comparatively large, but always smaller than that of the female; in some 

 of them f. i. Proales Wernecki both sexes are at birth almost equalh' large, whereas 

 the female grows larger later on. The cuticula is always thin. A sort of lorica is 

 present in Diglena forcipata (Weber). In the peculiar male of Herhvigia volvocicola 

 the foot is wholly absent; in the other males described, it is almost as W"ell developed 

 as in the female: the body is always extremely flexible, constantly changing its form. 

 Where the wheel-organ has been more thoroughly observed, a ventrally curved cilia- 

 covered disc of oblong often triangular form has almost always been found; it is 

 bordered by somewhat longer cilia; auricles may be present, but most probably they 

 are generally slightly developed. 



It is very interesting that the alimentary canal either seems to be developed 

 in almost the same degTee as in the female or, at all events, with conspicuous rudi- 

 ments; in Proales Wernecki even the mastax and the small gastric glands are present. 

 In the other species a longitudinally folded band or sac. lying above the testis, is 

 often and most probably always observed; in some of them gastric glands may be 

 present, a more thorough examination will most probably always show the lateral 

 antennæ. It will be of great interest to know the developmental stage of the re- 

 trocerebral organ which according to de Beauchamp's investigation, just in the 

 females of Xotommatidæ, has reached so high and so pecuHar a development. Our 

 knowledge with regard to the organ in the males is at present extremely small; only 

 of the male of Copeus pachyurus there exists a figure seen laterally (Dixon Xuttall 

 1893 Tab, XV) in which the whole organ is well drawn. Most probably this figure has 

 been unknown to de Beauchamp. The figure shows a long club-shaped sac strongly 

 attenuated in the forepart and with tw-o lateral sacs. Behind, the sacs are filled 

 with a granular mass, more anteriorly with something like a reticulated tissue. The 

 two openings for the organ I have seen in a conspicuous position in Xotommata 

 aurita. The excretory organ presents no peculiarities; the two lateral canals carry frorn 



