316 DR. JOHNSTON ON THE ACARIDBS OF BERWICKSHIllE. 



constant stops to its progress ; and with the claws extended, 

 the smoothest leaf of a Potamogeton, or the most slippery 

 soil, affords but an easier course to its race. 



This species cannot be identified with any described by 

 Muller or by A. Dug^s ; nor indeed can it strictly be re- 

 ferred to any of the genera into which the latter naturalist 

 has distributed the family. The mite belongs apparently to 

 the genus Atractides of Koch (Uebers. des Arachnidens. 

 Drittes Heft. p. 22), which contains six species. Of these the 

 names only are given in the book just quoted, and I have no 

 access to the larger work in which they are described and 

 figured. I am thus forced to remain ignorant whether our 

 species has been already noticed and named, — it is certainly 

 neither Atractides clavicornis nor A. spinipes ; — and in this 

 position I may be excused for bestowing upon it a name dif- 

 ferent from any yet borne by its genus. 



