44 Bulletin American Museum of Natural History [Vol. XLII 



From two to eleven eggs are in each case and these hatch in seven 

 to eleven days. When leaving the case, the larva seems to select no 

 particular place of exit. Specimens have been noticed emerging from a 

 hole in the egg-case proper; others from an opening made at the outer 

 edge of the basal cavity of the filament (see Plate IX). Many larvae 

 have been collected. They may be observed on the Cladophora and 

 stones just where the water laps the shore, half in water and half out, 

 as is the customary position of most pseudo- and metapneustic Hydro- 

 philidae. The number of instars seems to be three. 



About the middle of June 1915 several fairly mature larvae, which 

 were hatched from eggs taken April 29, were placed in the usual terra- 

 rium but, as they did not seem quite ready for pupation, they were 

 replaced. On June 22, while on a special trip to the best collecting 

 grounds of Laccobius, about fifteen larvae were taken. The largest of 

 these were placed in the terrarium at the same time as one of the 

 reared larvae but in different receptacles. On the morning of June 30 

 one of the latter lot had pupated as well as one of the larvae of April 

 29. Upon comparing the larval skins and pupae, they proved to be 

 identical and, so, one pupa was allowed to come through but the other 

 was preserved with its larval skin. Thus, the complete life history was 

 secured. One of the larvae pupated on the surface of the earth, while the 

 other made a cell (6 mm. long, 3 mm. wide, and 3 mm. deep), just below 

 the surface. The dates of development were as follows: 



April 29, egg-case found; May 4, larvae hatched; June 30, pupated; 

 July 3, adult emerged. 



Soon after emerging the adult's head, prothorax, and scutellum were 

 colored very dark green, except the lateral margins of the pronotum, 

 which were silvery gray with dark green or blackish spots sparsely 

 distributed. The coxae, trochanters, and femora were gray, but the tibiae 

 and tarsi were luteous. The exact time before complete coloration took 

 place was not noted, but it was longer than with other species. 



Egg-case, without its filament, nearly spherical, often a little broader than 

 long, its size varying as does that of the filament. Measurements show the case 

 proper to be from 1.4-1.6 mm. in diameter and the filament from 7-10 mm. in length. 

 The latter is continuous with the covering of the case and is therefore hollow, the 

 cavity at its base being quite large, as figure 11, Plate IX, indicates. 



Newly Hatched Larva. — Length, 2 mm.; width, 0.288 mm. Whitish (trans- 

 parent at first), except the chitinous portions, which are light brown darkening with 

 age. Integument dotted with slightly recurved spines arising from minute tubercles. 



Head quadrangular, elevated slightly; labro-clypeal suture weakly indicated by 

 a crease in the integument; frontal sutures parallel, extending to the caudal margin 

 of the head and not uniting to form the epicranial suture ; f rons quadrangular ; hypo- 



