FAUNA OF THE CHESS AND GADE. 345 



restless and its movements were too quick to enable its structure 

 to be fairly seen. Fig. 13 represents the Eotifer as it appeared, 

 partly contracted, after narcotization. 



23. Hydatina senta, Ehren. — This also is a Eotifer obtained 

 by me from one pool only, but while the single specimen of 

 F. molaris, above described, seemed to be in the collecting bottle 

 by accident, there is no doubt that H. senta was plentiful and 

 could scarcely be missed in the pool whence it was obtained. 

 This was a small, shallow pool on Boxmoor Common, in process 

 of being filled with rubbish, and containing water of a very dirty 

 appearance, although not muddy. In order to economize in the 

 use of my limited supply of collecting bottles, for I was going 

 as far as Dagnall, in the extreme north-eastern part of the 

 country of the Gade, the smallest collecting-bottle was used. 

 Examining the contents of this bottle a day or two afterwards, 

 a splendid specimen of H. senta was found and served excellently 

 for all purposes of microscopic examination of the species. 

 Although the water in which the Eotifer lived was repulsive to a 

 degree, the Eotifer itself was a beautiful object beneath the 

 microscope. The rounded prominences on its oral end carried 

 a number of styles which vibrated rapidly and, appearing like 

 so many flashing rays of light, produced quite a dazzling effect 

 on the eyes. The Eotifer often anchored itself, and sometimes 

 swam about slowly, constantly twisting about or doubling upon 

 itself. A large part of its alimentary canal was yellow or 

 greenish-yellow, but with a dark -coloured central part, and, 

 after narcotization, bright green Euglence were discharged in 

 large numbers from the cloaca. 



In the autumn of 1912 the above-mentioned pool swarmed 

 with Turbellarian and other worms, and no Eotifers were 

 obtained from it. On June 3rd, 1913, when the specimen 

 described above was obtained, the pool must have contained 

 very many specimens of H. senta. At the present time (July 

 14th, 1914), the pool is absolutely dry, and is so far filled in 

 that in the wettest season it will scarcely hold more than six 

 inches of water. As long as a pool forms there, however, this 

 Eotifer will probably be found, especially in spring and early 

 summer. In his account of the Eotiferan fauna of the region 

 of Lake Geneva, Mons. E. F. Weber says (Eevue Suisse de 



