Da. JOHNSTON ON TUB ACARIDES OF BERWICKSHIRE. 371 



the body, not very unequal but the two hinder pairs are 

 rather the thickest and longest, the second pair shortest, 

 bristled, tapering, six-jointed ; Ist small, 2d longer than the 

 3d which is a little longer than the 4th, 5th longer than the 

 second, the tarsal longer than it, conoidal, obtuse and fur- 

 nished with two curved subpedicled claws with a pulvillus 

 between them: Bristles of the legs scattered, not longer 

 (with a few exceptions) than the diameter of the joints, 

 those of the tarsal joint short and principally arranged along 

 its inner edge : Skin beautifully striolate, the striae being very 

 obvious and regular on the joints of the palpi and legs. 



The rostrum consists of a central triangular piece bifidly 

 divided at the apex and armed as already described ; and it 

 is sheathed between two large elongated mandibles which 

 are of a triangular form also, having a broad base and a 

 rather ^ddenly narrower point. These mandibles are equal 

 in length to the central piece and are terminated, on the apex, 

 with two minute neat chelae. This structure of the rostrum 

 is very similar to that of Acarus longicornis. 



This mite is scarcely half the size of the Acarus longicor- 

 nis, but they are alike in colour and in their Apion-like 

 shape. It varies a little in colour and in size ; and I have 

 seen specimens with pale legs when the body itself was 

 darker than usual. These variations undoubtedly depend 

 upon the individual's state of repletion. I have seen no eyes, 

 and their existence is at least very doubtful. 



Bdella vulgaris is common in many places of our district 

 It is found under stones and lichens on wall-tops and on dry 

 gravelly banks, for moisture is noxious to it ; and it may be 

 found throughout the summer and even in winter. It creeps 

 at a uniform moderately quick pace, — slower, however, con- 

 siderably than Acarus longicornis ; and readily runs back- 

 wards when stopt in its progress. In most specimens I can 

 see, on the anal extremity, a minutely bituberculated wart, 

 somewhat like the spinnerets of the spider ; and I have been 

 hence led to infer that this species may probably spin a web 

 for the protection of its eggs. 



27. Ixodes canisuga. 

 Ix. ovatus, scuto cordiformi punctato, abdomine albido 

 laevi integro nee marginato, pedibus ferirugineis. 



Desc. £odi^ obovate, compressed, of a skimmed milk-white 



