7 
On the Male of Rhinops vitrea. By G. F. Rousselet. 
a mystery; in some species degeneration lias been carried further 
than in others, whilst in Rhinops vitrea it seems to have yet scarcely 
begun. 
In a large number of families the males are now known ; the 
Philodinidae, however, form a conspicuous exception, as no single 
male of the genera Philodina , Rotifer , Gallidina , or Adineta has yet 
been discovered. It has been proved by M. Maupas that the so-called 
winter eggs (which occur at all seasons) are those which have been 
fertilised by males ; both Dr. Janson and Mr. D. Bryce have observed 
spiny resting eggs in several species of Gallidina, and it is therefore 
not too much to infer that male Gallidina must exist. May it not be 
possible that the males in this family have jaws like the females, and 
have been overlooked, because the moment a Philodine was seen to 
have jaws it has been dismissed as an impossible male ? I would 
suggest to those who have made this family their special study to look 
for males, with sperm-sac instead of ovary, amongst Philodine3 
showing fully developed jaws and digestive tract. 
I conclude this paper with a list of all Rotifers, 64 in number, 
whose males are known, with the names of the authors who have 
figured and described them : — 
Stephanoceros eichhorni Western, Dixon-Nuttall. 
Floscularia campanulata Hudson, Weber. 
„ mutabilis Hudson. 
„ calva Hudson. 
„ ambigua Hudson. 
„ coronetta Hudson. 
„ gossei Hood. 
„ pelagica Rousselet. 
„ cucullata Hood. 
Apsilus lentiformis Metschnikoff. 
Melicerta ringens Hudson. 
„ conifera Gosse. 
„ tubicolaria Hudson. 
„ janus Hudson. 
Limnias ceratophylli Gosse. 
I Fcistes mucicola Western. 
Lacinularia socialis Hudson. 
„ natans Western. 
Megalotrocha alboflavicans Anderson. 
„ semibullata Thorpe. 
„ procera Thorpe. 
Trochosphsera seguatorialis Thorpe. 
Gonochilus volvox Cohn, Hudson. 
„ unicornis Rousselet. 
Asplanchna briglitwelli Brightwell, Dalrymp^. 
„ priodonta Gosse. 
