18 Bulletin American Museum of Natural History [Vol. XLII 



Helophorus lacustris LeConte 



Plate II 



Two egg-cases were noted deeply embedded in moss at the water- 

 line and only the tubes were visible. The cases proper were covered 

 with sand and mud but the tubular filaments were clean and white. 

 Thirteen larvse were obtained from these cases and they made their 

 escape through the tubes. A preserved case shows three of the larvae 

 in the tube at one time, one behind another. Several other cases 

 were obtained in the laboratory, where they were laid in some alga which 

 had been pulled out of the water and placed on the side of the aquarium. 

 A part of the alga was left hanging in the water and this kept the re- 

 mainder moist. 



Egg-case 1 somewhat flask-shaped. Egg-case proper nearly round, measuring 

 1.69 mm. in width; tube, 0.94 mm. wide distally. The whole 4.84 mm. long; the 

 opening is obliquely across the end of the tube and extends 1.076 mm. down the side. 



Newly Hatched Larva. — Length, 2.55 mm.; width, 0.403 mm. Whitish 

 except chitinized portions, which are brownish with head yellowish in part; integu- 

 ment more chitinous than in other larvae and with only a few scattered setae. 



Head quadrangular, only slightly elevated, dorsal side one-half the ventral in 

 length, posterior margin with a prominent semicircular emargination; fronto- 

 clypeal suture weakly indicated, more prominent towards the middle; frontal sutures 

 converging gradually and joined by a short transverse suture contiguous with the 

 posterior margin of the head; epicranial suture absent; gula polygonal; gular sutures 

 confluent; cervical sclerites evidently not present. 



Labro-clypeus triangular (subcorneal) . Lateral expansion of the epistoma 

 prominent, similar, rounded, about even with the anterior margin of the labro- 

 clypeus and each bearing seven, stout, recurved spines; epipharynx spinous. 



Ocular areas in groups of six and closely aggregated; roundish; arranged in two 

 rows of three each and all equidistant from each other. The hind row set slightly 

 nearer the median line than the front row. 



Antennae short, slightly exceeding the mandibles ; first segment about as long as 

 the second, slightly constricted near the base; second segment widened towards the 

 tip, obliquely truncate, possessing distally in the membrane a pair of two-segmented, 

 lobiform antennal appendages on the outer side in addition to a strong seta and two 

 strong distal setse on the inner side; terminal segment cylindrical, much narrower 

 than the other segments and provided with several apical setae. 



Mandibles symmetrical, prominent, sharply pointed at their tips and with the 

 inner surface of the anterior piece serrate; two 2 inner teeth on each mandible about 

 equal in size; a strong medio-lateral spine present; molar areas smooth. 



J The egg-case of H. aguaticus figured by Schiodte differs greatly from our generic type and I doubt 

 his accuracy. 



2 H. granularis has only a single inner tooth. 



