433 



On Cyrtonia tuba = Notommata tuba (Ehrenbkrg). 



By Charles F. Rousselet, F.R.M.S. 



(JEtead September 21st, 1894.J 



Plate XX. 



This Rotifer was included in Hudson and Gosse's Monograph 

 as a British species on the strength of a sketch in Dr. Collins' 

 Notebook, but whatever this figure (H. and G., PI. XVII., Fig 8) 

 may represent, it certainly is not Ehrenberg's Notommata tuba. 

 This animal does not appear to have been seen again from the 

 time Ehrenberg discovered two specimens in Berlin in June, 1832, 

 until 1888, when Mr. G. Western found it at Staines, but just too 

 late to be mentioned in the Supplement, which was then in the press. 

 It has been obtained repeatedly since from the same locality, and I 

 found it in June of last year at our Club excursion to Hertford 

 Heath. Ehrenberg's description is extremely short and meagre, and 

 his figure, although very imperfect, just enables one to recognize the 

 creature. Under these circumstances, it seems desirable to place 

 on record a more extended description and more correct figure of 

 this very beautiful and interesting little Rotifer. 



The head is the broadest part of the animal, and thence the 

 body tapers down to the toes ; it is, therefore, somewhat trumpet- 

 shaped, and has from this appearance received its specific name. 

 From a side view it is seen that tlie body has three distinct bends : 

 the head is strongly curved vcntralwards at the shoulder, giving 

 the animal a humped appearance in this view ; the lower part of 

 the body is bent dorsalwards, and the two-jointed foot issues 

 again at an angle towards the ventral side, and frequently 

 the toes are also carried at an angle to the foot ; the bends are 

 quite constant and only the foot can be moved, but it is generally 

 carried at an angle to the body, as drawn in the figure. 



The corona (Fig. 2) is very large and unlike that of any other 

 Rotifer in its shape and appearance ; it consists of a broadly-oval 

 trochal disc, fringed with long and fine cilia all round. Within 

 this there are three ridges of longer and stouter cilia, or styles, one 

 at each side and one in the middle near the ventral edge. The 



