1920] Richmond, Studies on the Biology of the Aquatic Hydrophilidce 19 



Maxillse with palpifer not joint-like; stipes fairly large, swollen, not notice- 

 ably narrowed towards the apex, only a little longer than the palpifer, its inner 

 surface provided with a row of five stout seta?, another just inside the most distal 

 one and two slender seta? near the externo-distal angle; palpifer fairly large, a little 

 longer than wide, bearing an inner stout lateral seta; a slender seta in the externo- 

 distal angle and a slender cylindrical appendage in the interno-distal angle, exceeding 

 the first segment of the palpus, with sense-cones and a seta at its tip as well as those 

 nears its base; palpus cylindrical, tapering slightly with sense-cones at the distal end; 

 the second segment slightly longer than the other two. 



Labium not exceeding the mandibles, but prominent and just attaining the distal 

 end of the palpifer; submentum small; mentum not exceeding the tooth of the labro- 

 clypeus. cylindrical, a little longer than wide, and slightly swollen distally; palpiger 

 equal to the mentum in length, its sides diverging and forked distally; the palpi, 

 borne by the two forks, cylindrical and tapering; the second segment about twice as 

 long as the first and with sense-cones at the tip; ligula absent. 



Prothorax with angles obtuse; well indicated, only a little wider than the head, 

 sides parallel; anterior and posterior of pronotum non-chit inized; sagittal line 

 present; presternum chitinized in front and lateral to the coxa?. Mesothorax and 

 metathorax equal to each other in length but shorter than the prothorax and becoming 

 very slightly narrower than the latter caudally. The nota are entirely chitinized and 

 each bears a transverse row of four prominent setse. The sagittal line, which continues 

 throughout the eighth abdominal segment, prominent. A pair of bifore spiracles on 

 the mesothorax. 



Legs fairly long, slightly longer than the thorax is wide; coxa? transverse, grooved 

 laterally to receive the femora; femora a little longer than the tibia?; tarsi claw-like, 

 about as long as the latter and with no inner seta?; the anterior coxa? are closer 

 together than the four posterior coxa?, which are about the same distance apart. 



Abdomen with nine distinct segments, very slightly narrowed caudally. Anal 

 segment projecting, short and cylindrical; the first seven abdominal tergites similar 

 and resemble the meso- and metanota in the arrangement of the seta? and their 

 chitinization. Dorsally a row of four seta? on each segment, each seta emerging from 

 a broad, rough tubercled area, which is chitinized and separated from the others by a 

 longitudinal furrow or suture. Laterally two similar chitinized tubercled areas, the 

 posterior one larger and with a seta (both probably correspond with the epipleurite) ; 

 hypopleurite similar, one-lobed and with a seta. The sagittal suture very distinct as 

 well as the longitudinal furrows. Ninth segment narrower than the eighth and nearly 

 twice as long with a prominent lateral seta on each side, corresponding to the seta of 

 the lateral tubercled areas just mentioned; only the tergite is chitinized. Arising 

 from the posterior margin are two divergent, three-segmented, cylindrical, tapering 

 cerci. The first segment bears a ventral and dorsal seta, the second a terminal seta 

 just below the origin of the third segment, which has a terminal seta as long as the 

 three segments together. The three segments bear the relation of 16, 12, and 18 to 

 each other in length. Each spiracle 1 is just below and in front of the outer dorsal 

 tubercled area. First eight sternites with a transverse row of four tubercles, each 

 bearing a seta which has a small, chitinous plate at its base, and a small seta each 

 side of the median line near the anterior margin. Three transverse folds are present 



■ pared with the other Hydrophilidce, which possess them, the bifore spiracles are well developed . 



