I>. .1. SCOL'IJFIELl) 0\ KNTOMOSTRACA. 175 



from a very small pond — probably the smallest in the Park — 

 by the side of the " Heronry Pond." 



Biaptomus gracilis, G. 0. Sars. A most abundant species at 

 Wanstead Park. The majority of the males do not possess an 

 appendage at the end of the antepenultimate joint of the right 

 antenna, but I have noticed a few specimens in which this pro- 

 cess was well-marked. 



Cyclops signatus, Koch. 



Cyclops tenuicornis, Claus. Some evidence obtained by watch- 

 ing the later stages of development of this and G. signatus leads 

 me to think that they must still be regarded as distinct species, 

 and I have consequently kept them apart in this record. They 

 both occur all the year round, and in all the ponds. 



Cyclops Scourfieldi, Gr. S. Brady. Both the type and the 

 variety described by Prof. Brady have been found at Wanstead 

 Park, usually occurring together, but not constantly. They 

 have never been seen during the colder parts of the year. In 

 further illustration of this preference for a relatively high 

 temperature, it may be interesting to mention that the typical 

 form of this species was the only Cyclops found in the Victoria 

 Regia Tank at the Royal Botanic Grardens, Regent's Park, both 

 in April, 1891, and April, 1892. The water of the tank on the 

 latter occasion was about 80° F. 



Cyclops vicinus, UTljanin. I believe the active period of this 

 species is considerably shorter than would be imagined from an 

 examination of the record appended to this paper. The speci- 

 mens found in September, 1891, and June, 1892, were from the 

 " Shoulder of Mutton Pond " — a pond in which this species is 

 scarcely ever taken. It is possible, therefore, that these two 

 records are in some way exceptional. There can be no doubt 

 that at Wanstead Park the main development of this form is 

 from late November to May. It has never been found in the 

 " Perch Pond." 



Cyclops hicuspidatus, Claus. Two or perhaps more varieties 

 are here included under this name, one of which is probably 

 identical with the C. Thoinasi, Forbes, of Prof. Brady's " Re- 

 vision," but it is a matter of considerable difficulty to definitely 

 separate these forms, and it is possible that they may be only 

 stages in the development of one species. Like the foregoing 

 species, the present seems to reach its greatest abundance 



