1920] Richmond, Studies on the Biology of the Aquatic Hydrophilidce 53 



to rear any of them but they were very cannibalistic, constantly attack- 

 ing each other. About twenty-five were left for several clays in the same 

 jar and only one larva survived. Some fed readily on the Cyclops in 

 the jar but they were too ravenous to be satisfied. 



A number of larvae, apparently full grown, were placed in terraria 

 but they would not transform. Thej^ burrowed clown, making galleries 

 all through the earth, and even formed cells but never pupated. There 

 they lived for several months without food. All stages were found 

 throughout the summer and, in early spring, the partly grown larvae 

 were frequently taken under stones, leaves, or in moss. There they 

 were, half in water and half out, lying in wait for their prey. 



Egg-case, proper, nearly spherical and about 4 mm. in diameter. A flat, round 

 cap closes the upper end of the case and it measures 2 mm. across. The flare, which is 

 continuous with the cap, varies, but one half of it is usually quite broad while the 

 other half is narrow. 



Xewly Hatched Larva. — Length, 4.5-5 mm.; width at the thorax, 0.7-0.8 

 mm. Whitish, with light, yellowish brown, chitinized areas. The integument is 

 covered with small, fine, brown, setae. 



Head quadrangular, 0.6 mm. wide and 0.528 mm. along the mid-dorsal line; 

 front o-cly peal suture weakly indicated; frontal sutures irregular but converging 

 gradually and uniting to form a short epicranial suture; frons shaped somewhat like 

 an arrow-head; cervical sclerites present; gula reduced, pentagonal, rounded pos- 

 teriorly; the gular sutures prominent and confluent; articulating maxillary piece 

 distinct. 



Labro-clypeus prominent, asymmetrical and with five distinct, acute teeth; the 

 outer tooth on the left set apart from the other four teeth, which are equidistant; 

 six setae present, one on each side of each tooth. Lateral expansions of epistoma not 

 exceeding the labro-clypeus, rounded and each with a row of seta; at the anterior 

 margin. 



Ocular areas in groups of six but rather indistinct. They are arranged more or 

 less in a compact circle. The anterior three with their axes more longitudinal while 

 the posterior three have their axes more horizontal and the last, or sixth, area is more 

 remote than the others, which are nearly equidistant from each other. 



Antennae fairly short, not exceeding the mandibles; just about attaining the 

 distal end of the palpifer; the first segment constricted slightly in the middle and 

 about the same size as the second; the second segment swollen with a small, color- 

 Less, antennal appendage and several sense-cones at its externo-distal angle: a long, 

 slender, interno-distal seta present; third segment very much smaller than the latter 

 and provided apically with sense-cones, besides two long, slender setae. 



Mandibles symmetrical, prominent, stout, sharply pointed at their tips, and each 

 with three well-defined inner teeth. The most distal tooth is the largest, the middle 

 one a little smaller, and the proximal one considerably smaller. The molar area is 

 smooth and rounded. 



Maxillae with joint-like palpifer; stipes stout, tapering slightly ,with a row of 

 five setae on its inner surface; palpifer with a slender chitinous appendage, longer 

 than the first segment of the palpus and bearing a terminal seta at its disto-medial 



