30 Bulletin American Museum of Natural History [Vol. XLI1 



Labium barely exceeding the stipes of the maxilla, union of submentum and 

 mentum not clear but submentum probabty small while mentum is longer and cordi- 

 form; palpiger about as long as wide, cylindrical; palpus short; the first segment 

 about one-half the second, which has small distal seta? that are mounted on minute 

 tubercles. Ligula absent. 



Prothorax with sides rounded, of the same width as the head; entirely chitinized; 

 sagittal line present throughout the thorax. Meso- and metathorax similar, of the 

 same width but a little shorter than the prothorax. 



Legs not quite as long as the thorax is wide and robust; coxae oval, transverse 

 and with a dorsal groove; femora, tibiae, and tarsi all about the same length; tarsi 

 well developed, basal part long, claw-like and bearing two inner setae. 



Abdomen with eight distinct segments, all of the same width, ninth and tenth 

 rudimentary. The first seven tergites similar and intersegmental membrane not well 

 defined. Each segment covered with a dorsal plate, the anterior margin of which is 

 straight while the posterior is rounded; no prominent setae present but a lateral 

 inconspicuous seta. Bifore spiracles mounted on small tubercles, just inside and 

 anterior to the lateral seta. Pleural groove distinct. Each segment apparently with 

 a ventral plate corresponding in structure with the dorsal plate ; eighth segment with 

 sides only slightly rounded out, of the same width as the preceding one. It represents 

 the superior valve of the stigmatic atrium and its caudal border is four-lobed, each 

 lobe bearing a seta. 



Procercus, or process of the eighth pleurite, one-segmented with a terminal seta. 



Mesocercus (cercus) two-segmented, tapering, the first elongate dome-shaped, 

 the second about the same length but more slender and with a terminal seta and 

 covered with several small tubercles, each with an apical seta. 



Ninth tergite divided into three lobes, two lateral and one median; median lobe 1 

 small and a little longer than wide with its caudal margin nearly straight and bearing 

 a short but prominent seta at each caudo-lateral angle; outer or lateral lobes large, 

 rounded and with a terminal seta; acrocercus below and its distal end shows between 

 the lateral lobe and the median lobe just mentioned. 



6. Sphercheinse 2 



Egg-case carried by the hind legs and held on the under side of the body. Larva 

 with head slightly inclined; ocular areas round and in groups of five, not closely 

 aggregated; antennae with points of insertion nearer the externo-frontal angles than 

 those of the mandibles; epicranial suture very short, almost absent; labro-clypeus 

 very much reduced, the epistoma apparently limiting the front margin of the head; 

 mandibles stout, sharply pointed, furrowed internally and with inner teeth; maxilla 

 palpiform but with palpifer bearing an inner lobe or lacinia; labium with palpi 

 and ligula short; labium and maxillae inserted in a furrow on the under sid 8 of the 

 head; gula well developed and attaining the occipital opening. Eight complete 

 abdominal segments, the ninth and tenth reduced. The type of breathing is pseudo- 

 metapneustic and with poorly developed bifore spiracles. Seven pairs of short conical 

 gills on the first seven segments. Cerci and prostyles present but reducd. 



iThis median lobe seems to articulate at its base .and may be the remains of the tenth segment of 

 the lower Hydrophilida\ 



2 This subfamily is not represented in this country but is incorporated on account of its unique 

 specialization. 



