14-J TAOR SKOrrSHRRO 



Tho position of Cifpiiilimi ulhoiiiacuhtld. W . B\ll;l'. KStid ;i. p. 2(il, pi. J^XXI, li;;. 1 is 

 more uiu-ortain. Tliis sjJiH-ii's was placed by (i. W . .Mri,Li:i!, li)l'J, uikIci- the same hoadiiif;; as 

 the two forms jvist mentioned. ( 'n account of the size and shape of the shell and the airan^'e- 

 ment of tlie fi.xing spots of the shell muscles, it does not seem tn me impussiMe that this species 

 may also belong to this family, and that it is most closely related to the genus CijdaMcwfe. 

 lieltuinn- ■■/ u„ i„„r It seems still too earlv to give an opinion as to the mutual relations of the four genera 



grnrra mtniionfit ^j^^^^^ ^^.j^j^ above. It Can, howevcr, be said with a fair degree of certainty that Ci/danteropr and 

 (.'(/c/o/t'bfrw are comparatively closely related to each other. The genus Asterope, on the other hand. 

 occupies a comparatively isolated position. The same t h iiig may also be said of the genus Asterofteron. 



Occology of reprod\iction: — As in the case of the sub-family Cypridininae extremely 



little, or perhaps it would be more correct to say nothing at all, is known of the phenomena 



connected with the occology of reproduction in this family. I myself can unfortunately contribute 



ven^ little to the solution of this problem. 



So restricted \\\ the facts seem decidedly to support the view that in this family as well breeding is 



hreedmg perm . ^^^ limited to a moic OF less short period but takes place during the whole year. 



The method of breed- AMien Working at the material of the genus Asterope, so rich both in individuals and in 



'the 'enus Asterope? species, on which the present work is based, it was very striking to notice how exceedingly rare 



the males were among the mature specimens, in most species they were even quite missing. 



In investigating the last larval stages I observed, however, that the males and the females were 



about equal in numbers, in some cases the males were even decidedly in the majority (three 



to one); cf. A. Grimaldi, below. G. W. MUller had precisely the same experience previously 



(1894). As an explanation of this phenomenon he assumes (p. 13) that the males could escape 



the net owing to their superior powers of movement. ,,Eine andere Erklarung scheint mir 



kaum zuliissig" .... 



I cannot say for certain whether this explanation is correct. One m a y, however, 

 imagine another explanation, which seems even more probable. This is that we have in these 

 forms an oecology of reproduction which agrees with that which has been observed in the genus 

 Philotnedes. In other words after the last larval moult males and females live for a shorter or 

 longer period planktonically. During this planktonic life copulation probably takes place. 

 After copulation both sexes return to the bottom, the males dying comparatively soon after- 

 wards, the females returning to their burrowing or digging life. It is probable that the planktonic 

 life is longer in the case of the males than in the case of the females. 



The fact that on several occasions these forms were found in plankton strongly supports 

 the assumption of a planktonic copulation. I have myself found a male (undescribed) in the 

 plankton material collected by the Swedish South Polar Expedition. G. S. Bhady, in his 

 work 1868 a, p. 128 mentions that both A. Mariae and A. teres were caught planktonically, 

 „though never very abundantly". The same author adds: ,,It would seem, indeed, that these 

 animals do not come to the surface except after sunset". The same author mentions, 1898, 

 p. 431, that males of A. australis were caught ,, abundantly" in plankton in ,,Otago Harbour". 

 But females seem also to have occurred in the find in f|uestion, as is indicated by the following!; 



