British Oribatidce : Notes on New ami Critical Species. 219 
Colour a very dark vinous brown, without any prodorsal 
spot ; surface of the dorsal plate rather dull, minutely reti- 
culate (diameter of mesh about 12 /x). 
Abdomen broad oval, wide behind. Pteromorphae 
normal, but their thickened fore margins are joined by a 
median extension in the form of a narrow lunette, separated 
from the dorsum by a transverse fold. This and the ptero- 
morphae are of a slightly yellower hue than the dorsum. 
Dorsal hairs none. 
Lamellae nearly upright behind, extremely oblique in 
front, conforming pretty nearly with the very slight in- 
clination of the translamella. Projecting limb broad, 
concave, forming two acute cusps with an angular notch 
between from which springs the terminal seta. The setae 
are serrate, curving inwards beyond the rostrum. The 
interlamellar setae are also convergent but straight, serrate, 
sloping forwards and meeting beyond the cusps of the 
lamellae. Tectopedia very large and prominent. 
West Allendale, Northumberland ; Derwent Valley, 
Durham. Very like picipes in general appearance, but 
easily distinguished by the absence of the prodorsal spot 
and the lack of dorsal hairs. Like picipes it is fond of 
' ascending into shrubs. 
O. ovalis Koch. 
O. nitens Nic. 
O. QUADRICORXUTUS Mich. 
O. TECTUS Mich. 
O. hasticeps sp. n. (Plate A, fig. 2). 
O. redux sp. n. (Plate A, fig. 1). 
This is another group of closely related forms. Quadri- 
cornutus may be separated at once by its bifurcate lamella; 
and the conspicuously plumose setae of the cephalothorax ; 
moreover, like tectus, it has no triangular lobe on the fore 
margin of the pteromorphae. This lobe is present in all 
the others and separates them from all other British members 
of the genus. Of these four, ovalis is by far the most abun- 
dant. It varies in size from 400 to 700 /x, always retaining 
however, its distinctive barrel-shaped abdomen, dull, 
densely punctate cuticle, and characteristic dorsal hairs. 
The first and last of these characters it shares with nitens ; 
and as the sole remaining difference berween these two is 
merely a matter of texture, nitens must rank as a variety of 
ovalis. The two other forms are here described. 
O. hasticeps sp. n. (Plate A, fig. 2). 
Length from 400 to 500 j a. 
Colour very dark purple brown, polished but rather dull, 
with a yellow oblong prodorsal spot. Abdomen orbicular. 
Prodorsal margin running to an obtuse point in the middle. 
1914 Julyl. 
