FAUNA OF THE CHESS AND GADE. 343 



violent was the attack that it seemed likely that the Rotifer 

 would have its foot and toes torn off, and its lorica so mutilated 

 as not to be worth sketching. When found again the Eotifer 

 was lying in a somewhat tilted position on its side quite dead, 

 and with its oral part injured, this being bitten or broken so as 

 to present jagged edges. Immediately after the attack two of 

 the numerous specimens of infusorians (Coleps hirtus, Ehren.), 

 which had been swimming about without attempting to molest 

 the Rotifer while living, buried themselves to some extent in its 

 injured oral parts. Fig. 11 represents the Rotifer and its assail- 

 ants at this time. Other specimens of the same infusorians did 

 the same, so that, at different times, there were three, five, six, 

 and eight of them attacking the dead Rotifer. The total length 

 of the Rotifer was nearly ^ in. ; that of the infusorians was 

 about gJo in. The only other specimens of D. trigona obtained 

 were dredged from Kings Langley Lodge Pool on April 13th, 

 1914. 



20. Eretmia cubeutes, Gosse. — In the year 1913 specimens 

 of this Rotifer were obtained from the pools of Parsonage Farm 

 and Chipperfield Common. Usually the numbers obtained were 

 small, but on one occasion, March 24th, 1913, the Rotifer was 

 exceptionally common in Parsonage Farm Pool. The lorica 

 was ellipsoidal, but with the oral part truncated and presenting 

 a toothed edge, with the teeth regular in size and shape. A 

 most striking feature of this Rotifer is the mosaic-like pattern of 

 its lorica, the elements which correspond to the squares of an 

 ordinary mosaic being arranged diagonally and having little 

 pyramids built upon them. With this arrangement of the 

 elements the surface of the lorica presents a large number of 

 pointed knobs, and the oral teeth are simply the pointed corners 

 of the foremost row of elements. 



The specimens usually swam about rapidly, at the same 

 time rotating about their long axis ; the dorsal and ventral 

 processes and the four posterior spines could not be counted 

 while these rapid movements were going on, the effect being 

 usually to produce an impression of two well-defined spines, 

 always in focus more or less distinctly. Sometimes the Rotifers 

 assumed a vertical position, remaining practically in the same 

 place and appearing like rotating toothed wheels. 



