244 ENTOMOLOGICAL NEWS. Qune, '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 Oribatidse. 



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 lamellae. The cephalo- 

 thorax bears three prominent pairs of large, stout, pectinate bristles 

 (PL XI, Fig. i) ; 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 i. 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 



