THE TAPEWORMS (CESTODA] OF THE RED GROUSE 345 



know what the cysts of either Davainea urogalli or Hymenolepis microps were like ; 

 and, secondly, the tissues of the insects and spiders which we examined are little, 

 if at all, known, and more than once we have at first sight taken some organ proper 

 to the insect for a cestode cyst, only to our great disappointment to discover later 

 that we were looking at an ovum or other structure belonging to the putative host. 



During some days Dr Wilson and I spent in Edinburgh towards the end of 

 July 1908. we examined a considerable number of the commoner insects found on 

 the moors in the hope of throwing some light upon the life-history of the tapeworms 

 so common in the Grouse. The specimens we investigated were collected by Mr 

 P. H. Grimshaw, who has prepared a Report on the Insects of the Moors. We are 

 greatly indebted to him and to the Keeper of the Museum, Mr W. Eagle Clarke, 

 and to Mr. J. Ritchie, for kindly placing at our disposal a workroom and other 

 accommodation which greatly facilitated our work. When the insect had not been 

 specifically named, we always kept a similar specimen for subsequent identification 

 in case it should contain the cyst ; but, alas ! here again our labour was in vain. 



In the manner indicated we examined the following insects, in every case look- 

 ing through the debris of some four or five specimens. 



DlPTERA. 



(i.) Monophilus ater, one of the subfamily Limnobiime of the Tipulidae. A 

 very common constituent of the food of young Grouse. No trace of a cyst was 

 found, but in one specimen an immature nematode was wriggling about. 



(ii.) Bibio sp. Here again we drew a blank. 



(iii.) Cyrtoma spuria, one of the Empidse. This fly is small, and seemed to 

 have little interior ; no trace of a cyst was found. In another small empid fly we 

 discovered a Gregarine. 



(iv.) Scatophaga sp. Scatophaga stercoraria is perhaps the commonest fly 

 in Scotland, and, owing to the larva living in the droppings of the Grouse, it can 

 hardly fail to contain the eggs of the cestodes ; but we have never found a 

 Scatophaga in the crop of a Grouse, and there is some reason to doubt if the tape- 

 worm eggs develop in this fly. After searching for a long time, through the tissues 

 of many specimens of Scatophaga, we only managed to find one ovum apparently 

 of Davainea urogalli, and that was no further advanced than when it was laid. 



PLECOPTITRA. 



Similar gropings through the disjected membranes of an unknown species of 

 perlid produced no better results. 



