122 



Dr. Johnston on the Acarides of Berwickshire. 



able to describe it correctly; for when crushed so as to be made 

 an object for the microscope, the parts are dislocated and con- 

 fused. There are two strong mandibles laid parallel to each 



other, and each of them terminated with a pair of minute curved 

 claws, one of which only is moveable. External to each man- 

 dible, and perhaps adnate to it, there is a slender jointed palpus ; 

 and underneath ? the mandibles a pair of triangular plates 

 (labrum), from the point of which protrudes a sharp bristle or 

 stylet (fig. b). 



This mite is tardigrade. It resembles a small Cercyon, and 

 is covered with a skin of the same coriaceous character as the 

 cases of that beetle. When crushed, the skin is shown to be of 

 the same fine ferruginous colour as the legs, deriving its darker 

 hue only from the thickness of the viscera it encloses. The 

 largeness of the basilar joints of the legs is surely a singular 

 character in an insect which does not leap, and so slow and 

 deliberate in its walk. I cannot conjecture a reason for this 

 collection of muscular power in the limbs. In the fore legs the 

 basilar joints are elliptical (fig. c); and the second joint of the 

 second pair has a narrow wing or border (fig. d) on the inferior 

 edge. 



The mite is common. It lives in moss on walls, and I have 

 found it on agarics in spring and summer. 



I refer the insect to the genus Carabodes of Koch; but I 

 could not discover any clavate bristle on the thorax, although 

 attention was directed particularly to this character. 



