THE ECTOPARASITES OF THE RED GROUSE 369 



OSTRACODA. 



Cyclocypris sere7ia (Koch). 



COPEPODA. 



Diaptomus gracilis (G. 0. Sars). 

 Cyclops viridis (Jur.). 

 Cyclops sei'vulatus Fisch. 



Also the common fresh-water Amphipod, Gammarus jpulex (De Geer.) 



A complete list, so far as was known at that time, of the Entomostraca of the 

 Highlands and of the Lowlands could be extracted from the very useful Synopses 

 published by Scourfield in the Journal of the Quekett Microscopical Club during 

 the years 1903 and 1904. 



In none of the species examined have we yet succeeded in finding any cysts. 



We have thus with some degree of probability shut out as the second or larval 

 host of the tapeworms — at any rate for the present — the ectoparasites of the 

 Grouse, the myriapoda and the slugs or snails, and the fresh-water Crustacea, and 

 this on the grounds (I) that on examination none of them reveals a cyst, and 

 (2) that these animals are either not eaten by the bird, or so rarely eaten 

 and in quantities so small as to render it highly improbable that any of these 

 invertebrates could account for the almost constant presence of the cestodes in 

 large numbers in the Grouse. 



Two rather striking facts seem to point to the normal insect food of the Grouse, 

 which it picks up on the moor, as the more probable source of the tapeworms. 

 One is that two of the artificially reared Grouse at Frimley, which died during 

 the early autumn of 1907, were carefully searched for tapeworms, but neither 

 Davainea nor Hymenolepis was found. The second fact is that young Grouse 

 often contain fully-grown Davainea before they are three weeks old. They must 

 certainly have swallowed the second host when very young, perhaps even the day 

 they were hatched, or the worm would not have had time to grow. Hence our 

 best chance of finding this second host is to examine the crop-contents of the 

 very young birds, and to do this we must have a moor at our disposal, and 

 leave to kill as many young birds as we may want. 



I have been assured over and over again by sportsmen and gamekeepers that 

 the Grouse eats no insects ; but this is far trom the truth. 



VOL. I. 2 a 



