48 Bulletin American Museum of Natural History [Vol. XLII 



procedure may be is a question. Possibly it may serve to aerate the film 

 of air, thus accounting for their ability to remain below the surface 

 almost indefinitely. Stridulation is very pronounced and Brocher 

 considered it in detail. 



About thirty egg-cases were laid the middle of April in the aquarium 

 on alga and moneywort below water. They somewhat resembled 

 miniature chestnuts in form, and each contained from two to four eggs. 



The first egg-cases noted out of doors were found May 9 in a small 

 pool on South Hill. The submerged Carex was spotted with the white 

 cases and apparently the dead plants were preferred. In a pool where no 

 vegetation was present the cases were laid upon the under side of sticks 

 and stones. Although more abundant in the egg-laying seasons, com- 

 mon to the family, yet the cases were found during the entire summer. 



The larvae on hatching break through the case at no particular 

 place. However, the most common point of exit was between the base 

 of the flap and the cap. The larvae were very weakly chitinized in com- 

 parison with the larvae of other genera. They spend most of their time 

 crawling through the strands of algae or in the debris at the bottom of the 

 aquarium. The larvae are the most difficult of the whole family to locate, 

 due primarily to the fact that they breathe by gills. They live at the 

 bottom of the ponds and farther from the shore than is the custom of the 

 other larvae. The debris clings to them and they, therefore, closely re- 

 semble their surroundings. 



Berosus peregrinus Herbst 



Plate X 



Several egg-cases of B. peregrinus were found the latter part of 

 July and the spinning and egg laying proceeded in the following order. 



1. An under layer of compact silk, composed of criss-cross 



strands, laid down continuous with the flap. 



2. One egg deposited lengthwise towards one side and covered 



with a loosely applied silk. 



3. Second egg placed near the opposite side, parallel to the 



first egg and covered with a loosely applied silk. 



4. Third egg laid between the first two eggs. 



5. A cap of compact silk, composed of criss-cross strands of 



silk laid tightly over the egg-case proper. 

 Egg-case, as a whole, somewhat chestnut-shaped. The cap end is flat with a 

 narrow flare outside the egg-case proper; and the cap, which covers this surface, is 

 continuous with the slender filament that extends upwards. The other end is rounded. 



