FAUNA OF THE CHESS AND GADE. 163 



These peculiar movements, when once seen, can be easily 

 recognized again ; and, as far as I know, are characteristic of 

 Eotifers of the genus Adineta. 



42. Polyarthra platyptera, Ehren. — It has already been stated 

 that a distinguishing feature of the rotiferan fauna of Chipper- 

 field Common Pool is its unusually large number of so-called 

 " Skipping Eotifers." At any season of the year, specimens of 

 these can be obtained there. The commonest is Triarthra 

 longiseta ; a second less common species is Pedetes saltator ; a 

 third species, Polyarthra platyptera, occurs in the pool, but 

 seems to be much rarer, for only one unmistakable specimen of 

 this species has so far been obtained, and that specimen was 

 dead. The oral end of the Eotifer was truncated, and the 

 posterior end was rounded. The width of the body was rather 

 more than half its length. There were two clusters of broad, 

 serrated spines, one cluster springing from the right and the 

 other from the left side of the oral end of the body. Only eight 

 spines were counted, and as this species has twelve spines 

 altogether, the other four had evidently been broken off or 

 decayed. The longest spines were half as long again as the 

 body of the Eotifer, and the innermost pair were symmetrically 

 placed, one on each side, and met at their extremities so as to 

 form with the front part of the Eotifer a triangular figure. 

 This single specimen of the species was obtained on April 13th, 

 1914, together with a few specimens of 

 Anurcea brevispina, the rotiferan fauna of the 

 pool on that date being very poor. 



43. Notommata lacinulata, Ehren. — This 

 very small Eotifer has been found in small 

 numbers in many localities of the country of 

 the Chess and Gade. The form of the Eotifer 

 is shown in Fig. 19, drawn from a specimen 

 obtained from Parsonage Farm Pool, Abbot's 

 Langley, on April 11th, 1914. This specimen 

 was measured and found to be about ^Jo-inch 

 long. The greater part of the body was 

 occupied by the stomach, which was filled with 

 a large quantity of food material of a brown 



colour. This Eotifer often anchored itself to the slide with its 



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