1920] Richmond, Studies on the Biology of the Aquatic Hydrophilidce 23 



through middle but widely separated; two set* just posterior and outside the former 

 tubercles and two others posterior but inside the latter tubercles, both in a horizontal ' 

 row. The lateral expansions of the epistoma not prominent. Epipharynx apparently 

 not spinous. 



Ocular areas round, five on each side, not aggregated; the first and second not 

 seen from above, fairly close together and placed one back of the other just behind 

 the insertion of the mandible at the side; the third and fourth about the same distance 

 apart as the first two and located just posterior to the insertion of the antenna, the 

 fourth more dorsal and posterior; the fifth widely separated from the fourth, more 

 lateral and posterior. 



Antenna? three-segmented, 1 fairly long, exceeding the mandibles; first segment 

 more than twice as wide as long and less than one-third the second segment in length ; 

 latter about the same width, slightly constricted in the middle and with an outer 

 spelling just proximal to the middle, bearing a small, blunt spine; distal end with four 

 long setae; third segment slightly constricted and distally with several prominent seta?. 



Mandibles approximately symmetrical with broad bases, their tips with several 

 finger-like processes, the arrangement on two mandibles differing somewhat; lacinia 

 mobilis present, pectinate distally; molar area with numerous spinules and two 

 inner teeth in front of it. 



Maxilla? with palpifer joint-like and seeming to form the first segment of the 

 palpus; a large internal lobe present, which clasps the stipes on the ventral side and 

 shows a tendency to be divided distally into two lobes; the outer lobe tapers to a 

 sharp point while the inner lobe is shorter, blunter, and fringed with a row of stout 

 seta? distally as well as with several slender seta? nearer its base; cardo noticeable 

 and as broad as the stipes at its union; stipes wider and longer than the palpifer and 

 with two lateral seta?; palpifer about as wide as long; palpus tapering; second seg- 

 ment slender and only slightly longer than the first; terminal segment very small 

 and somewhat flask-shaped. 



Labium with palpi barely exceeding the labrum, short; submentum, reduced, 

 transverse, indistinct; mentum broad but longer than wide, slightly constricted; 

 palpiger transverse, slightly forked; palpus short, two-segmented, articulating 

 membranes well developed; second segment narrower, shorter than the first, its 

 margin flared distally and with apical seta? and papilla?; ligula present, barely ex- 

 ceeding the first segment of the palpus, rounded and furnished with papilla? (very 

 similar to Limnebius). 



Prothorax with sides and angles rounded, of the same width as the head . Pro- 

 scutum well developed and entirely chitinized, sagittal line present; anterior and 

 posterior margins with a transverse row of seta?; a median transverse row of seta? 

 and several lateral seta?. 



Mesothorax a little shorter than the latter, slightly narrowed in front. Meso- 

 scutum well developed and entirely chitinized, less conspicuously in front; sagittal 

 line present; a transverse row of seta? just in front of the middle and at the posterior 

 margin; several lateral seta?. Metathorax the same. Sterna not noticeably chitinized. 



Legs fairly long, about as long as the thorax is wide; coxa? transverse with a 

 dorsal groove; femora about the same length as the tibia? but a little stouter; tarsi 

 slightly more than one-third the latter, claw-like and with no inner seta?. 



^Articulating membrane at. base very prominent but non-chitinized. 



