32 Bulletin American Museum of Natural History [Vol. XLII 



dead leaf makes it more difficult to see them. They float freely and are 

 the most picturesque of all the egg -cases. A case was formed indoors on 

 April 22 and, as there were no leaves present in the aquarium, it was 

 placed in a mass of floating algae. No definite air chamber such as is 

 found in Hydrous is present. The eggs, about forty in number, are laid 

 in a vertical position at the bottom of the case. Just behind the cap is 

 a mass of loosely spun silk. The cap end is never covered by the leaf 

 but the larvae do not always emerge underneath it, as seems to be the rule 

 in Hydrous. More often the escape is made at the other end. 



The young larvae fed readily on Cyclops, Cypridopsis, etc., and made 

 several attempts to catch small tadpoles. Freshly killed tadpoles were 

 placed within their reach but they evidently did not care for the dead 

 food. According to Bowditch, they become full grown in about thirty 

 days and spend the remainder of the summer and winter as pupae, 

 emerging early in the spring. Such an extraordinary length in the pupal 

 stage may be true but it does not sound plausible nor is it always the case. 



In July a mature larva was captured floating in the middle of a 

 lagoon near the Biological Field Station. It was placed in a terrarium 

 and on July 21 started burrowing down. After several attemps to 

 form a suitable cell below the surface, it finally pupated above ground 

 July 28. The process of transformation took less than an hour and a 

 beautiful sea-green pupa resulted. Five days later the adult emerged. 

 At the time of emergence the beetle was piceous above but its under 

 side was light brownish in color. 



Egg-case. — Whitish except brownish mast and plate at its base. Case without 

 the leaf 9.2 mm.-18 mm. long, 9.8 mm.-ll mm. wide, and 7.8 mm.-9 mm. high. The 

 horn-like mast, arising vertically from the top of the largest or cap end of the case, is 

 from 7 mm.-ll. 8 mm. in length. It is enlarged at the base into a roundish plate about 

 4.-4.5 mm. high. The top of the mast is often bent forward and away from the case. 



Newly Hatched Larva. — Length, 6.5-7 mm.; width at the thorax, 1.25 mm. 

 Light brownish in color. Integument entirely pilose. 



Head broadly ovate, constricted behind, elevated; front o-clypeal suture well 

 indicated at the sides; frontal sutures gradually converging but not uniting until 

 they attain the caudal margin of the head; frons raised in the middle; gula reduced, 

 arched, semicircular, and with the gular sutures prominent and confluent. Cervical 

 sclerites present. 



Labro-clypeus nearly symmetrical, reduced, with very small inconspicuous 

 teeth at the anterior margin and a row of five small setae equidistant from each other. 

 Lateral expansions of epistoma similar and broadly rounded, overlapping the bases 

 small short setse along their margins. 



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

 vertically, while the posterior three are horizontally placed. The sixth area or outer 

 one of the posterior row distant from the fifth. Articulating maxillary piece fairly 

 well developed. 



