118 Dr. Johnston on the Acarides of Berwickshire. 



sameness in the structure of the palpi, but in S. latirostris, 

 I think, the mandibles are stouter, the back is more convex and 

 glossy, and the skin shows no appearance of strise under the 

 magnifier. 



31. Ammonia megacephala. 



A. ruhida dorse irregulariter infuscato sparse setoso, rostra pedi- 



busque clarioribus. 

 Ammonia megacephalat Koch. Ubers. 75. tab. 9. fig. 42; 



Walck. Ins. Apt. iv. 531. 



Desc. Mite ovate-oblong, narrower and rostrate in front, soft, 

 of a reddish colour with dusky blotches on the back, the rostrum 

 and legs paler and clearer. Body divided into rostrum, thorax, 

 and abdomen, llostrum longer than the thorax, triangular, 

 rather suddenly narrowing about the middle, furnished on the 

 sides with three sharp slightly curved bristles, and the apex with 

 a coronet of minute setse. Eyes four, a pair on each side at the 

 suture which divides the thorax from the abdomen, of a red 

 glossy colour. Abdomen convex, slightly indented at the sides, 

 sparingly covered with short bristles, rounded and entire behind. 

 Legs as long as the body, gracile, somewhat tapered, bristly, 

 the fourth pair longest, then the third, and the two anterior 

 pairs a little shorter; first joint minute, second elongate, third 

 and fourth short and equal, fifth as long as both of them, sixth 

 elongate, tapered, armed with numerous strong short setse on 

 the inner or inferior side, suddenly angled near the extremity, 

 and furnished with a pair of claws with an intermediate cushion 

 or pul villus. Skin very minutely striolate. 



The rostrum is made up of a central piece, and of two man- 

 dibular shafts, each terminated with a pair of small neat chelae, 

 the larger claw only being moveable. The palpi arise from near 

 the base of the rostrum, and are nearly twice as long as it ; they 

 are filiform, geniculate, bristly, five-jointed; the basal joint 

 minute, the second elongate, the third and fourth small and 

 equal, the fifth nearly as long as the second and a little slenderer, 

 with the apex armed with two long subequal bristles ; and the 

 bristles on the sides are longer than those on the lower joints. 



This mite is quick in its motions ; and, when arrested in its 

 progress, it backs with alertness. I found the specimen in my 

 garden. The species is not represented by Hermann, but it 

 agrees in many respects with his Scirus longirostris. It be- 

 longs to Koch's genus Ammonia,sind may be his Am.megacephala ; 

 but the terminal joint of the palpi is represented in this to be 

 naked, and there are a few longer bristles on the legs, which we 

 did not notice in our mite. 



