36 Bulletin American Museum of Natural History [Vol. XLII 



doors at the edge of the pools under stones, debris, or even some distance 

 from the shore on the surface of the alga-filled pools. The larvae are 

 found all summer but this first generation of the year is the most abun- 

 dant. The second generation begins soon after the adults emerge, the 

 greatest number of egg-cases of this generation being found the first 

 part of August. 



Pupae were secured about the same time of the year within their 

 cells an inch below the surface of the bank or under stones. When 

 transforming indoors, many of the pupae did not form a cell below ground 

 but changed at the surface. The cells formed were about 12 mm. wide, 

 10 mm. high and nearly round. The earth in the terraria was only 

 about three-quarters of an inch deep so that the larva could be observed 

 forming the cells next to the glass. The constant squirming of the larvae 

 made the cell walls firm. The legs, especially the fore legs, helped materi- 

 ally in shedding the pupal skin. The tarsi are bent back and the tibiae 

 used in pushing the skin off. 



Upon emerging, the head of the beetle, the middle of the pronotum 

 (the edges lighter), the scutellum, and the legs were brownish in color. 

 The elytra were yellowish white and the abdomen whitish. It colored 

 very rapidly and in about ten hours was entirely black above but slightly 

 brownish below. 



Egg-case. — Whitish, except brownish mast. The measurements of case, which 

 is figured, were 9.3 mm. long; 4.2S mm. wide at the cap end; 5.3 mm. wide at the 

 other end; and the mast 4.8 mm. long. 



Newly Hatched Larva. — Length, 4.8 mm.; width at the thorax, 0.84 mm. 

 Light brownish (fulvous). Entire integument covered with fine short hairs. 



Head ovate; fronto-clypeal suture well indicated at the sides; frontal sutures 

 gradually converging and uniting to form a very short epicranial suture ; frons raised 

 in the middle, nearly triangular and with a transverse impressed line near its basal 

 third; gula reduced, arched and semicircular but flattened posteriorly; gula sutures 

 prominent and confluent. Cervical sclerites present. 



Labro-clypeus nearly symmetrical, reduced, with very small teeth, usually five, 

 in the middle and one on each side of the latter five but removed a little ; a transverse 

 row of six setae just inside the margin. Lateral expansions of epistoma similar, rounded 

 but somewhat straight in front, only barely exceeding the labro-clypeus with a row of 

 inconspicuous setae on the inner side and overlapping the bases of the mandibles. 



Ocular areas in groups of six and arranged in parallel rows, the first three nearly 

 vertically while the posterior three are horizontally placed. The sixth or outer one of 

 the posterior row is distant from the fifth and in some specimens is rudimentary. 



Antennae extending forward about as far as the tips of the mandibles and beyond 

 the first segment of the maxillary palpus; first segment longer than the following two 

 segments taken together but stouter than in the other Hydrophilinae; second segment 

 slightly more slender and with several short setae in the membrane preceding the third 



