1920] 



Ewing: Genus Trombicula Berlese 



383 



being variable. Palpi each with four inner tibial spines, the longest of 

 which is equal to about half the length of the claw. Thumb of palpus 

 not surpassing the claw. Abdomen with the usual constriction. Setae 

 of abdomen much longer on the posterior margin than on the shoulders. 

 Each seta is situated on a pedicel bearing disc, is strongly pectinate and 

 usually stoutest at its tip, where the barbs are somewhat less con- 

 spicuous. Legs rather stout, the anterior pair much the longest and 

 largest, the posterior pair reaching the tip of the abdomen. Tarsus I is 

 one and sixty-one hundredths times as long as tibia I and is much 

 thicker dorso-ventrally than laterally. Tarsus IV about one and a 

 fourth times as long as tibia and with the outer claw slightly smaller 

 and more strongly curved than the inner. Length usually from 1.00 mm. 

 to 1.10 mm., but varies considerably; breadth from 0.50 mm. to about 

 0.65 mm. 



Fig. 1. Trombicula coarctata Berlese; a, seta from dorsum of abdomen; X 900; 

 b, dorsal view of cephalothorax, X 375; c, last two segments of right 

 front leg, side view, X 125. 



Several individuals received from Dr. Miyajima from Japan. 



This species strongly resembles T. splendens Ewing, when 

 examined superficially, but in reality is quite distinct. It is a 

 blind species, whereas T. splendens has eyes, which, however, 

 are not strongly developed and are easily overlooked. The 

 posterior lobes of the pseudostigmatic area in the Japanese 

 species are angulate and situated directly behind the pseudo- 

 stigmata. In T. splendens these are evenly rounded and are 

 situated approximate at the median line. In T. coarctata the 

 pseudostigmatic organs arise from the pseudostigmata and are 

 distinctly pectinate ; in T. splendens these structures arise 

 inside the pseudostigmata and are either simple or but very 

 slightly pectinate. The body setae of the Japanese species are 



