C. Warburton 
273 
quently in all the varieties of Scircoptes he was able to examine (vide supra). 
Munro (1919) figures, but does not mention, two small spots in front of the 
plastron which are probably Megnin’s “rudiments of stigmata.” (PI. XV, 
fig. 10.) 
On either side of the notothorax, just posterior to this “plastron,” there 
are three notothoracic cones , arranged in a triangle with its apex posterior. 
These “cones,” which are in fact somewhat lancet-shaped, are articulated 
into the crater-like centre of circular low eminences. 
On either side of the notogaster are seven backwardly directed spines, 
roughly arranged in two longitudinal rows, an inner row of four and an outer 
of three spines. These spines are of the same nature 
as the notothoracic cones, but more elongated. These ^ _ \y" 
spines, cones and scales are all calculated to render 
retrograde movement in its burrow impossible to the 
parasite. 
The chaetotaxy, or arrangement of bristles, is 
especially important and none of the figures of the 
early investigators are accurate in this respect. 
Munro (1919), who both studied the literature on the Text-figure l. Dorsal scales 
subject and examined much fresh material, gives it 
as follows: 
On the notothorax there are four pairs of bristles: 
(1) a pair “lying just below the camerostome.” This appears to refer to 
the largest of three pairs of bristles which he figures as arising from the 
rostrum (see PI. XV, fig. 10). 
(2) a small pair close together near the anterior border. 
(3) a pair of strong whip-like bristles, one on either side of the clairiere 
and a notogastric spine 
of S. scabiei (after Fiirst- 
enberg). 
or plastron, and reminiscent, as Munro says, of the pseudostigmatic organs 
of the Oribatidae. As a matter of fact it is quite common in various acarine 
groups (Gamasidae, Tyroglyphidae, etc.) to find strong bristles in this position, 
and it is possible that they have a special sensory significance—as they cer¬ 
tainly have in the Oribatidae. When Fiirstenberg, however, alludes to 
the Tasthaar” he means the stronger of the two lateral hairs mentioned 
in (4). 
(1) a pair of bristles (or hairs) on each side just anterior to the fold 
separating notothorax and notogaster, the anterior (and according to Munro’s 
figure the more dorsally inserted) bristle being the longer. (This is Fiirsten- 
berg’s Tasthaar.) 
On the notogaster there is a pair of bristles on either side of the terminally 
situated genito-anal aperture, the inner bristle being somewhat longer than 
the outer. 
Ventral aspect. The rostrum and legs will presently be described in detail, 
but it is necessary here to mention the epimeres, which are striking features 
of the ventral surface, and have been considered of great taxonomic im- 
18—2 
