COTYLE RIPARIA. 83 



The agility and quickness of the latter fly is astonishing : it runs in under 

 the feathers about the shoulders ; and although the bird may flutter a good 

 deal, the insect is not disturbed ; nor does its presence cause uneasiness, 

 though it is said to make quite a sore place at times, and red spots. When 

 driven out, which it is with difficulty, it resumes its position immediately. 

 Sometimes these flies, of which the body is hard, will slip through the fingers 

 and get into the men's whiskers. 



It is to be presumed that when the Swallow and the Linnet migrate 

 they take their respective parasites with them ; but this I am unable to state 

 as a fact. They would seem to quit a dead bird very shortly after its life is 

 gone, and to have an immediate apprehension of something wrong when you 

 handle their living host. Both are figured and described in Francis Walker's 

 ' Insecta Britannica ' (vol. ii. pp. 287—289, and pi. xx.) ; also in Curtis's 

 'British Entomology' (vol. xiii. pi. 585). 



I have specimens of these flies found on the Starling, Wheatear, 

 Blackcap, Whitethroat, &c., but have not determined the species in each 

 case. All taken this season. 



Two Whitethroats were caught, and put into a cage. One was 

 examined, and a fly came out, but escaped ; instead, however, of going 

 in another direction, it immediately made straight for the other Whitethroat, 

 and went under its feathers. This bird was so marked as to be known, 

 and was allowed to depart on a Monday. Next Saturday it was again 

 captured ; and on it was seen a fly, supposed (but, of course, only supposed) 

 to be the very individual above mentioned. The bird was certainly the same. 



As regards Sand-Martins, it seems strange that an insect-eating 

 species should be infested with external parasites to such an extent ; but 

 they appear to do no harm, any more than internal ones, of which 

 Van Beneden mentions a most remarkable instance (pp. 90 & 91) : — 

 " Nathusius speaks of a Black Stork which lodged twenty-four Filarice 

 lohatcB in its lungs, sixteen Sijngami tracheales in the tracheal artery, 



N 2 



