210 THE ZOOLOGIST. 



its length was found to be about -^ in. Its long and slightly 

 curved toe was approximately as long as the rest of the animal. 

 The very short styles at the base of the toe were seen, but only 

 with difficulty. The central part of the Rotifer was brown, and 

 the rest was almost colourless. 



Another specimen, obtained on April 28th. 1913, from a 

 small pool, a little to the east of Hastoe and close to the bend of 

 the Hastoe and Cholesbury Eoad, measured g 1 ^ in. in total 

 length, and presented the features mentioned above. The 

 water of this pool was exceptionally clear and transparent, but 

 a few months ago the pool was completely filled in with clay 

 and gravel. 



9. Synchceta tremula, Ehren. — This small and very active 

 Rotifer is fairly common in the watercress beds of the Chess and 

 Gade, and in a few pools in which the water is clear. The 

 specimens I have examined have been chiefly from the Cashio 

 watercress beds, near Watford, and from Chipperfield Common 

 Pool. The movements of S. tremula are so characteristic that, 

 apart from the conical form of the animal and its small size, 

 they serve at once to identify it. A description of the 

 movements of one very active specimen, obtained on October 

 3rd, 1912, from the Cashio watercress beds will make this 

 clear. 



While examining two specimens of Amphileptus in a drop of 

 water from the aforesaid beds, the illumination of the field being 

 very brilliant, the Synchceta suddenly shot across the field. 

 Being altogether unprepared for its appearance, the only im- 

 pression it produced was that of a minute flash of light. Paying 

 no further attention to the specimens of Amphileptus, I quickly 

 moved the slide so as to enable me to follow the Rotifer, which 

 was soon found spinning rapidly about its axis, which was 

 vertical and practically stationary. Owing to its rapid rotation, 

 the only impression produced was as shown in fig. 7. After a 

 few seconds, the Rotifer darted across the field, appearing like 

 a cone moving base forwards. Following it again, the Rotifer 

 was found swinging itself in a very tortuous course about a piece 

 of debris to which it was anchored by a very fine thread extend- 

 ing from its toes, as shown in fig. 8. This thread, as is 

 well-known, is secreted by the foot-glands of the Rotifer. For 



