208 THE ZOOLOGIST. 



started to swim, with expanded wheels, until they met other col- 

 lections of mud and organic matter which were similarly explored. 

 At other times they remained anchored for a long period. 



The specimens of this Eotifer varied much in size, but were 

 usually about -^ in. long. The largest I have seen was, as far 

 as I could measure it, g 1 ^ in. long, when fully expanded. This 

 Eotifer was washed from a silk net which had been dragged for 

 a long distance along the canal, below Hunton Bridge, on 

 November 12th, 1913; it was almost the only form of life 

 obtained on this occasion. It was, however, the finest specimen 

 of its species that I have ever examined, and its movements on 

 the slide were all that could be desired to display its form and 

 allow of sketches being made. After moving about on the slide, 

 in water quite free from mud or organic matter by which its 

 movements could be concealed, it anchored itself and scarcely 

 moved out of the field for about half an hour. During this time, 

 the Rotifer repeatedly extended and withdrew itself slowly so as 

 to assume sometimes the form shown in fig. 4, and sometimes 

 that shown in fig. 5, stretching itself so fully that its joints 

 appeared as very fine lines, its external contour being almost 

 unbroken. In these positions, the whole of the foot was not 

 seen, but occasionally the Rotifer threw itself smartly from the 

 position shown in fig. 4 into that shown in fig. 6. At such times, 

 the full length of the Rotifer was seen, but never for more than 

 a second, for it always quickly resumed the position shown in 

 fig. 4 or fig. 5. Its exceedingly well-displayed movements, its 

 elegant tapering form, its small, round red eye-spots, and the 

 beats, about two per second, of its jaws against the anvil, were 

 all well seen. The figures do not, I think, exaggerate the 

 elegance of form of this Rotifer. 



7. Rotifer macrurus, Schrank. — This large and well-known 

 Rotifer, which is much less common than R. vulgaris, has been 

 obtained chiefly from the Chesham Road, Langleybury, and 

 Parsonage Farm Pools. From none of the water samples taken 

 from any of the pools has the number of specimens of this 

 Rotifer been large; in samples, e.g., obtained from the Parsonage 

 Farm Pool, on September 6th, 1912, and yielding fourteen 

 specimens of Salpina mucronata and six of Noteus quadricornis, 

 only one specimen of R. macrurus was obtained. 



