The Zoologist— March, 1869. 1587? 



and in this species are of a blood-red colour : the abdomen is made 

 up of segments, varying in different species from six to nine; the legs 

 are three-jointed, terminated with a wrist (?), a pad and ten sharps 

 crooked claws. The antennae are placed on each side of the head; 

 they are four-jointed, but vary in different species: these antennae are 

 often placed in a notch on each side of the head : this is particularly 

 the case in the long-headed sort. The insects are usually, in a greater 

 or less degree, covered with hair. In the parasite of the turnstone the 

 abdomen is very thickly covered with hairs : those of the eagle and 

 snowy owl are also very hirsute ; others, again, as in the greenshank 

 and little gull, are comparatively free from hair. 



Parasites are far more commonly found on some species than on 

 others : they are common on the birds of prey and also on some kinds 

 of sea-fowl. The fulmar petrel is very subject to them. The Corvidae 

 also often swarm with these creatures : this is particularly the case 

 with the hooded and carrion crows. They are few, and rarely found, 

 in the golden plover, and more rarely on the snipe : I have frequently 

 searched numbers of these birds without detecting a single insect. 

 What part they play in the economy of the bird, and whether they 

 effect it for weal or woe, it is difficult to determine. I find, as a rule, 

 that where a bird is in an unhealthy state, very poor, or suffering from 

 some old injury, that then they are most numerous. This is also the 

 case with some mammals: the sheep fag is always most abundant 

 when sheep are in poor condition, or have been shrinking, and when 

 cattle shrink they often become lousy. I have seen birds so infested 

 with these creatures that life must have been insupportable : they 

 swarmed like ants in an ant-hill, and must undoubtedly have 

 exercised a prejudicial effect on the life of the bird. Birds in the 

 highest condition I have found invariably the freest from parasitic 

 insects. 



The eggs of parasites are usually attached to the feathers. lu 

 a fulmar petrel the eggs or egg-cases were very firmly attached to the 

 shaft of the feather, some of the barbs being enclosed. Under the 

 microscope this egg appears to be built up of small particles, like a 

 martin's nest. 



There is a great field for investigation in connection with these 

 minute parasitic insects : I trust, therefore, that these few remarks 

 may induce some of my readers to take up the subject and prosecute 

 the inquiry. If it becomes an established fact that every species has 

 its own characteristic parasite it would be interesting to know whether 



