222 DR. JOHNSTON ON THE ACARIDES OF BERWICKSHIRE. 



two first pairs are inserted nigher each other than they are 

 to the hinder pair ; each leg has six joints, tlie four proximal 

 nearly equal, the fifth longer, the sixth still more elongate 

 and suddenly narrowed at the insertion of the claws. 



This mite may be compared to a grain of cayenne-pepper, 

 which it closely resembles in colour and in size. Some spe- 

 cimens are very exactly oval, but the majority are roundish 

 or somewhat cordate. In some there is a conical process at 

 the anus. The body and legs arc of the same colour. The 

 skin is very finely striolate under a high magnifier. 



In the course of the present summer I received from a 

 friend many specimens of this mite, which, he informed me, 

 was very troublesome to horses, cattle, sheep, dogs, and rab- 

 bits, and to the " herd's bairns,'" and people engaged about 

 the infested animals. It adhered to the skin, and in num- 

 bers occasionally so great as to be collected into small clus- 

 ters, hanging like a drop of congealed blood from the hairs. 

 They produced extreme itchiness ; and, says my correspond- 

 ent, " in the worst case I have seen, that of a horse, the 

 skin seemed exactly as if it had been rubbed with a liquid 

 blister." Hence I infer that the mite had penetrated be- 

 neath the skin, as I know it does easily into that of man. 

 When ex£^mining it, some individuals got upon my hands, 

 over which they dispersed themselves with considerable 

 quickness, and in a few seconds they had burrowed in the 

 skin so deep as not to be perceived, but the place in which 

 they had burrowed was indicated by itchiness, and by a blis- 

 ter that exactly resembled the pustule occasioned by the 

 sting of a nettle. One individual was watched. Jts race 

 over the hand and the moment of its fixation was unfelt ; 

 neither was any uneasiness felt by its penetration of the 

 skin. On getting under the cuticle it was killed by a strong 

 squeeze. No itchiness ensued, nor blister ; and the dead 

 insect remains, after an interval of more than three months, 

 unaltered, as is proved by the red speck that still marks the 

 spot of its death and burial. 



This troublesome insect prevails all along the sea-coast of 

 East Lothian. In Berwickshire it is rare, but is found on 

 farms near the sea-shore where the soil is light. It begins 

 to appear in the early part of July and is very troublesome 



