394 BRITISH ORIBATIDiE. 



Average length of legs (third pair) about '15 mm. 

 Average length of legs (fourth pair) about '17 mm. 



In identifying this small and variable species with 

 Koch's Opi)m splendens it must be understood that I 

 select it as being a common and typical form among a 

 number of minute and closely allied creatures, all of 

 which Koch probably included in his species ; indeed 

 it is more than likely that he had not the means of 

 distinguishing them. 



Colour light yellow-brown. 



Texture polished, without any punctures or mark- 

 ing visible by an amplication of, say, 200 diameters. 



Cephalothorax rather longish, slightly constricted 

 at the base. Rostrum rather rounded, although with 

 a median non-projecting point, as shown in the draw- 

 ing ; frequently just the points of the mandibles project, 

 giving the rostrum a much more pointed or sometimes 

 a trifid appearance. Rostral hairs very fine. Lamellae 

 ridges of moderate length, usually springing from the 

 edge of the abdomen, so that there is a short portion 

 behind the pseudo-stigma; the principal length starts 

 from the front of the pseudo-stigma and runs first 

 forward, then obliquely inward and forward, then 

 straight forward again, with sometimes a slight final 

 turn outward ; the ends are separated by a considerable 

 distance. The proportions and precise form of the 

 different portions of the lamellae vary considerably in 

 different specimens. There are not any lamellar hairs. 

 Nearer the median line are two shorter ridges which 

 often seem to start from a slight median projection of 

 the abdomen and run outward and forward, then turn 

 at a sharp angle and run inward and forward, then 

 straight forward or else outward and forward, in 

 which latter case they sometimes turn inward again at 

 a sharp angle, so that each ridge forms two zig-zags. 

 There is considerable variety in these ridges, the 

 drawing may probably be taken as about a type-form. 

 No translamella. Pseudo-stigmata rather projecting. 



