158 ANNALS OF SCOTTISH NATURAL HISTORY 



The specimens were taken on Hirta, the main island of a group 

 of four which are collectively called St. Kilda. The other three are 

 known as Boreray, Soay, and Dun. Mr. Waterston's stay on the 

 island extended from iyth June to lyth July inclusive, and from 

 information since received it appears that the weather conditions 

 were unusually favourable for insect life. The Diptera formed by 

 far the largest part of the insect fauna noted. In one little patch 

 the marsh they rose in swarms on hot days. In the evenings col- 

 lecting was done by sweeping, and on one occasion over 2000 

 specimens were obtained in a quarter of an hour. On some days 

 hardly anything new was added to the previous captures, as Mr. 

 Waterston made it a rule that if he recognised a species he took as 

 little of it as possible. Some species, however, occurred with per- 

 sistent regularity, and consequently the rule was occasionally broken 

 unconsciously. Under these circumstances it is, therefore, important 

 to note that the number of specimens of a species in the collection 

 is no clue to the frequency of its occurrence on the island. The 

 occurrence of Ccelomyia mollissima is of particular interest. It was 

 only seen on a single day on a ledge about 100 feet from the top of 

 the cliff and 400 feet from sea-level. This ledge was covered with 

 a good layer of blackish earth enriched by droppings of puffins and 

 other organic debris. The place was moist, had a luxurious vegeta- 

 tion, and in June and July the heat was great in the forenoon. 

 C. mollissima occurred on every buttercup, and the point of interest 

 was that, as this fly usually frequents moist woods, it occurred here 

 on St. Kilda only on the one spot where the conditions were 

 similar. 



THE ROYAL SCOTTISH MUSEUM, EDINBURGH. 



ON THE SCOTTISH SPECIES OF OXYURA 



II. 1 



By P. CAMERON. 



SCELIONINAE. 



THE species of this group are parasitic in the eggs of other 

 insects. Says Dr. Ashmead of them in his " Monograph of 

 the North American Proctotrypidae," p. 137, "This group is 

 probably the most extensive in the whole family, and of the 



1 Part i., antea, p. 34. 



