130 SMITHSONIAN MISCFXLANEOUS COLLECTIONS VOL. Ill 



branch of impression (loim) extending approximately three-fourths 

 distance from transverse branch to posterior transverse row of setae. 

 Anterior part of each mediotergite with 4 (rarely 5) setae arranged 

 as follows: i at end of transverse branch of impression, i toward 

 middle of transverse branch, i larger seta laterad to longitudinal 

 branch of impression, and another large seta near center of sclerite 

 equidistant from branches of impression ; rarely with a minute seta 

 between end of transverse branch of impression and middorsal suture. 

 Posterior part of each mediotergite with transverse row usually of 5 

 setae on more anterior segments, increasing to between 7 and 10 setae 

 on seventh and eighth segments (sometimes also on sixth and fifth 

 segments) ; setae not definitely paired, but 4 most medial hairs fre- 

 quently in semipaired arrangement; in the more posterior segments 

 some of the additional setae are placed between the primary hairs 

 and slightly farther caudad. Laterotergite I (Itg I, fig. 25, e) ex- 

 tending length of segment, with 3 setae. Spiracles subequal in size, 

 situated in posterior end of subovate sclerite, which is slightly wider 

 than spiracle and 2 to 2^ times as long ; in anterior half of segment. 

 Pleurites (pi) inconspicuous ; reduced to extremely narrow, elongate 

 sclerite usually infolded between laterotergite I and sternum ; bearing 

 I seta. Sternum (st) of i piece; subquadrate; without definite im- 

 pressions or sutures; several setae along lateral margins, sometimes 

 more abundant in eighth segment. 



Ninth abdominal segment (fig. 25, h), exclusive of urogomphi, 

 slightly shorter than eighth abdominal segment and three-fourths as 

 wide; four-fifths as long as wide; sides of anterior half subparallel, 

 posterior half tapering caudally making width at anterior margin of 

 caudal notch about two-thirds greatest width of segment. Dorsum 

 convex anteriorly, flatter posteriorly; sloping downward from front 

 to back. Dorsal plate (dpla) irregularly lined; sparsely punctulate 

 anteriorly; 4 faint longitudinal impressions, 2 laterally (lim) and a 

 paramedial pair (pirn) which converge posteriorly but do not meet; 

 with 2 long setae anteriorly, rarely with 2 small setae farther caudad ; 

 lateral margins slightly raised and carinate, bearing 3 prominent blunt 

 setiferous tubercles or "teeth" (to) ; transverse impression (trim) 

 usually interrupted in middle, rarely continuing completely across 

 segment. Tergite continues uninterruptedly laterally and on posterior 

 ventral surface; usually with from 12 to 16 setae on each side, some 

 issuing from small, sclerotized tubercles ; anteriorly on lateral aspect 

 with a transverse row, or a confused double row, of conspicuous pits. 

 Distance between posterior margin of pleural area and anterior margin 

 of caudal notch approximates one-fifth to one-fourth the total length 



