258 BRITISH TYROGLYPHID^. 



the feather, when they diminish rapidly. The barbs 

 are arranged in a single line on each side of the rachis, 

 and are horizontal. Each barb makes a slight angle 

 with the rachis, and runs outward and slightly forward 

 in a tolerably straight line until it has attained almost 

 the full width of the feather, when it suddenly turns 

 forward, and runs almost parallel to the rachis ; at the 

 extreme tip there is frequently a slight tendency to 

 curl outward again. Each barb comes to a point. 

 The barbs are simple, without barbules. Both rachis 

 and barbs are hollow ; the proximal end of each hair is 

 embedded in the cuticle. 



Rostrum not usually visible from the dorsal aspect ; 

 mandibles (PL XI, figs. 8, 9) rather attenuated distally, 

 tridentate on the fixed arm, quadri- or quinquedentate 

 on the moveable arm of the chela. 



Body. Abdomen raised in the middle, and also at 

 the hinder part, so that the antero -lateral portions of 

 the body are depressed and somewhat thin. The 

 wart-like projections show all along the edge. On the 

 abdomen, about opposite to the eighth pair of peri- 

 pheral hairs, is a single pair of very long thick hairs 

 which are closely set with fine spines on all sides, and 

 extend much further back than any of the other hairs. 

 The bursa copulatrix (PL XI, fig. 21) is a conspicuous 

 truncated curve about *03 mm. in length. The vulva 

 (PL XI, fig. 19) is very large, extending in the median 

 line from a little behind the epimera of the second pair 

 of legs to quite as far back as the hind angles of the 

 insertions of the fourth pair of legs. At the anterior 

 end it is strengthened by a compact block of chitin, 

 convex forward ; from which the large, slightly chiti- 

 nized labia run backward and outward; the whole 

 is surrounded by an elliptical band or plate, very 

 slightly chitinized, and bearing three pairs of small 

 fine hairs. The sternum is well marked but very 

 short, about 15 n ; the epimera of the first pair 

 of legs are joined to it; the inner ends of the other 

 epimera are free. On the under side there is a pair of 



