146 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Ill 



First to eighth abdominal segments siibequal ; first segment short- 

 est; fourth to sixth segments widest. Mediotergites (mtg, fig. 27, d) 

 with few small, shallow pits; transverse branch of impression (trim) 

 shallow, slightly sinuate, on second to eighth segments reaching from 

 one-half to three- fourths distance from longitudinal branch to mid- 

 dorsal suture, shorter on first segment ; longitudinal branch of im- 

 pression shallow, variable in length, extending from one-half to nearly 

 total distance from transverse branch to posterior transverse row of 

 setae. Anterior part of mediotergite without setae. Posteriorly on 

 each mediotergite, transverse row of 5 setae on second to eighth seg- 

 ments, only the most lateral seta being unpaired ; only 3 setae in poste- 

 rior row on the first abdominal segment. Usually i small seta, rarely 

 2, along margin of mediotergite laterad to impression. Spiracles {sp, 

 fig. 27, d) subequal in size, in anterior half of segment except in 

 eighth abdominal segment where spiracle always in posterior half. 

 Spiracular sclerite (spsc) well developed, subovate ; usually wider than 

 spiracle and 2 to 3 times as long as spiracle, increasing in size from 

 first to seventh segment, smaller in eighth segment. Laterotergite I 

 {Itg I) extending length of segment ; i large seta on dorsal margin. 

 Pleurite large, subovate, with i large seta. Sternum of i piece, sub- 

 quadrate ; 4 faint impressions, indefinite except on the more anterior 

 segments ; with i stout seta at each corner. 



Ninth abdominal segment (fig. 27, c, d), exclusive of urogomphi, 

 about as long as eighth abdominal segment and three-fourths as wide ; 

 almost as long as wide ; sides of anterior half subparallel, posterior 

 half tapering caudally making width at anterior margin of caudal notch 

 two-thirds (or less) greatest width of segment. Dorsum convex, more 

 pronounced anteriorly. Dorsal plate (dpla) sloping downward from 

 front to back, usually with a short transverse concavity slightly caudad 

 to the 2 setae found near the middle of the plate; irregularly lined 

 and wrinkled, but without pits ; 4 faint longitudinal impressions, 2 

 laterally (Urn) and a short paramedian pair (pint) in anterior part of 

 plate ; lateral margins slightly raised and carinate, bearing 3 prominent 

 blunt "teeth" (to), each with a long bristle; transverse impression 

 (trim) feeble, usually interrupted in middle. Tergite (tg) continues 

 uninterruptedly laterally and on posterior ventral surface ; usually 

 with from 5 to 10 unpaired setae on each side, some issuing from 

 small sclerotized tubercles. Distance between posterior margin of 

 pleural area (pi) and anterior margin of caudal notch from one-sixth 

 to one-fifth of total length of segment (exclusive of urogomphi). 

 Pleural area well developed, membranous, transversely striate. Ster- 



