82 Annals of the South African Museum. 



probably has the function of supplying the embryo with nutriment 

 from the surrounding fluid (1888a., p. 54, pi. 7, fig. 25). 



As I have previously pointed out the embryos vary much in si ze 

 amongst themselves, those nearest the external orifice being evidently 

 much older and much further developed than those nearer the ovarial 

 end of the duct. This is well shown in fig. 20, in which, however, 

 the oldest embryos are still comparatively small. In fig. 19 two 

 embryos taken from the dissected type specimen are shown, and the 

 largest of these, which lay nearest the external opening, is almost 

 ready for birth, while the other is one of the smallest in the uterus. 

 It is evident that the births of the young individuals take place at 

 considerable intervals and in various months of the year, although I 

 have not yet been able to ascertain the exact seasons. 



In a recent paper Bouvier (1900&, p. 68) states that he has con- 

 vinced himself that the females of several Peripatopsis contain 

 embryos of various stages of development, differing in this respect 

 from other forms of the genus, such as P. capensis and balfouri, 

 which are remarkable for the uniformity of their development. 

 Unfortunately Bouvier does not give particulars as to what extent he 

 found these embryos to differ amongst themselves. 



It may be advisable here to explain more fully the conditions 

 which I have observed in the numerous specimens of Peripatopsis 

 dissected by me (mainly belonging to balfouri, capensis and leonina). 

 During the earliest period of the development, particularly in cleavage 

 stages, it may be clearly demonstrated that the embryos of the same 

 brood in one uterus form a series in successive stages of develop- 

 ment, each one being slightly, although often scarcely perceptibly, 

 more advanced than the embryo on the side furthest from the external 

 sexual opening. The difference between embryos at opposite ends 

 of the oviduct is, however, very distinct and noticeable in these early 

 stages. In the later stages, when the legs have been formed, it 

 becomes no longer easy to observe any difference, except perhaps 

 a slight one in size, but at the time of birth the differences in develop- 

 ment again become evident, for the young are not all born at the 

 same time, but during a period extending over a number of days or 

 even several weeks, only a small number being born on each day. I 

 have myself observed this in P. moseleyi from Natal, and the Eev. J. 

 E. "Ward also informs me by letter that in his experiments on breed- 

 ing this species one young seemed to be born each twenty-four hours, 

 until the litter was complete.''' A detailed account has been given by 



* This observation has, I understand, been published in Jouni. Quekett Micr. 

 Club (2) vi., pp. 424-428, 1897. 



