244 ENTOMOLOGICAL NEWS. [June, ’08 
domen is oval and bears a large median boss or tubercle on 
the posterior end. | 
This genus resembles somewhat Lohmannia Michael, but 
differs from it in having three claws at the tip of the tarsus 
instead of one; in having the abdomen terminate posteriorly in 
a large swelling or tubercle; also in the shape of the abdomen, 
which is not cylindrical as in Lohmannia, but is oval, as in 
most Oribatide. 
Tumidalvus americana n. sp. 
Light brown; posterior part of the abdomen much darker than the 
rest of the body. 
Cephalothorax almost as broad as long; no lamelle. The cephalo- 
thorax bears three prominent pairs of large, stout, pectinate bristles 
(Pl. XI, Fig. 1) ; those of the anterior pair, situated near the tip of the 
rostrum, are about one-half as long as the cephalothorax and are di- 
rected forwards; at about the middle of the dorsal surface of the 
cephalothorax is situated a similar but slightly stouter pair of bristles, 
equal in length to the anterior pair; there is a much larger posterior 
pair of bristles situated almost approximate to the posterior margin 
of the cephalothorax, between the pseudostigmata; they are directed 
outwards and are about one-third longer than the middle pair. The 
pseudostigmata (Fig. 3) are prominent, cylindrical in shape, and about 
one-half as broad as the tibia of leg 1. The pseudostigmatic organ 
has a long, straight peduncle and a small clavate head; it is about two- 
thirds as long as the posterior pair of bristles. 
The abdomen is about three-fifths as broad as long; the surface is 
covered with rather small, round tubercles of almost uniform size (Fig. 
7); on the median posterior aspect ‘of the abdomen there is a large 
swelling or tubercle, already mentioned as a generic character. The 
dorsum of the abdomen bears twelve pairs of stout, pectinate bristles 
(Fig. 4). There are two rows of six bristles each on the dorsum, one 
on each side of the median line and not far from the same; the 
bristles in these rows increase in size from the anterior pair back- 
wards; the anterior pair is about one-fifth as long as the posterior 
pair. There is a row of six subequal bristles on each side of the ab- 
domen, on or slightly above the lateral margin. Genital and anal 
covers contiguous (Fig. 5); genital covers about two-thirds as long as 
anal covers, and each bearing on its inner margin eight stout, short, 
sharp spines, which point inwards; anal covers very long and narrow, 
each bearing near its outer margin two prominent stout bristles, 
which point inwards; each bristle is about twice as long as the width 
of the anal cover at the point where it is situated. 
Legs stout and short, the anterior pair being about three-fifths 
