481 



NOTE ON PROALES (NOTOMMATA) Gl G ANTE A Ql.fiSCOTT, 

 A ROTIFER PARASITIC IN THE EGG OF THE WATER- 

 SNAIL. 



By John Stevens, F.R.M.S. 



(^Read April 2'Srd, 1912.) 



Plate 24. 



In the summer of 1892 Miss Glascott discovered in Ireland,, 

 inside the eggs of the common Water-snail, a parasitic Notom- 

 matoid Kotifer which she named Notommata gigantea, and 

 figured and described in her List of some of the Rotifera of 

 Ireland,* but which, apparently, has not been observed since. 



Early last year, in corresponding with Miss Glascott, she 

 suggested I should keep a sharp look-out for Rotifers in the 

 eggs of water-snails. I did so, and in June was fortunate 

 enough to find several promising clusters of the eggs in the 

 well-known jelly-like masses. There were plenty of the snails 

 Lhnnaea (Eadix) auricidaria Linn, and Pcdudina vivipara Linn, 

 present, so it is reasonable to assume that the former species 

 was responsible for the eggs. 



I could see at once that a considerable number of the eggs 

 were infested with Rotifers. It was equally plain that with 

 Notommata gigantea in mind it was not difficult to come to the 

 conclusion that this animal was the same, which later was con- 

 firmed by Mr. C. F. Rousselet, to whom I sent some mounted 

 specimens. 



Miss Glascott's description of the general appearance and 

 characteristic features of this species is quite good, but the 

 figures are unfortunately inadequate, and do not give a fair 

 idea of the creature. 



There can be no doubt that this rotifer belongs to the genus 

 Proales rather than Notommata, having much in common as 



* Sc. Proc. Roy. Pub. Soc. Vol. VIII. (N.S.), 18'J3. Part I. pp. 29-SG, 

 5 PI. 



