ACARINA FROM THE JUAN FERNANDEZ ISLANDS 603 
3rd joint short, triangular in outline, with two slender hairs, one external, 
one internal, curved forwards and upwards. 4th joint short, with two long 
dorsal hairs in the middle and one marginal ventrally which curved forwards 
and upwards like an S on the exterior side. 
5th joint long, cylindrical, about 3 times as long as its diameter, cut off 
obliquely from the dorsal side at the top, where there are three very slightly 
curved, hyalin, pointed bristles of subequal size, arranged like the teeth of a 
comb; a little in front of the middle there is a larger, slightly curved, hyalin 
bristle, inserted on a low projection, which as pointed out by the author (1910, 
p- 496—497) in reality consists of two bristles pressed closely together; behind 
this there is a curved hair of medium size. 
Hysterosoma. The hairs of the dorsal side are either very inconspicuous 
or absent. The arex porose on the other hand, are very conspicuous, after 
proper treatment with lactic acid. The area porose adalares are large, eongated, 
with rounded ends, tapering outwards and about 4 times as long as they are 
wide; they are transversal, with the longitudinal axis forming an almost right 
angle with the lateral margin of the body and finely punctured. 
Only one pair of arez porosz mesonotice, which seem to be shaped like 
a horse-shoe with the concavity turning inwards. As a matter of fact at greater 
magnification the ares appear to be oval, on the lateral side surrounded by a 
narrow band of slightly thickened cuticle; on the inner side there are two 
rounded lobes of subcutaneous glands (fig. 108). With oil immersion the arex 
seem to be densely covered with exceedingly minute cuticular spines, but the 
structure is very difficult to see plainly and it may be that what appears to 
be spines are in reality fine canals penetrating the cuticle of the arez porosz. 
Near the hind margin there is a pair of large, rounded arez porose pos- 
teriores, the longest diameter of whichis 4/5 of that of the areze porose ada- 
lares; between them there are about 5 pairs of smaller, rounded pores and on 
lateral view we notice a row of small rounded pores along the sides, not visible 
from above. 
The pteromorphe project forwards almost as far as the top of the 
rostrum, the fissure is very distinct and directed forwards parallel to the an- 
terior edge of the pteromorphe. When the pteromorpha is dissected and 
viewed from above the fissure is seen to be a groove, rounded inwards, where 
it is broader and gradually disappearing towards the middle of the pteromorpha. 
The anterior edge of the pteromorpha is concave, forming an even and sym- 
metrical curve, the lateral edge has a wide, rounded incision. 
Loc.: Juan Fernandez, Masatierra, among dry leaves Aug. 1917. 
18. Pergamasus crassipes (L.) var. longicornis BERLESE. — Figs. 109—110. 
This very widely spread species seems either to be subjected to a great 
variation, or else it is composed by several closely related species, the males 
of which have almost the same armature of legs II. 
