66 NATURAL HISTORY OF AQUATIC INSECTS CH. 



It was whitish, of the size of the end of the finger, 

 nearly spherical but rather oval and flattened. The 

 surface, which looked like tow, was not quite smooth. 



A 



Fig. 14. — Cocoon of Hydrophilus. A shows the mast ; B is opened to expose the 



eggs. From Miger. 



One of the two ends was flatter than the other, and 

 furnished with a raised rim. From the space within 

 this rim projected a sort of little tapering mast, about 

 as long as the cocoon. 



" I opened several of these cocoons, and found in 

 each about a hundred eggs. They were white and 

 oblong, regularly arranged side by side with the points 

 upward, and though provided with a double covering 

 were so transparent that a day or two before they 

 were hatched one could see the animal within. The' 

 head appeared bent upon the thorax as in a pupa. 



" The larvae, when hatched out, remained one day 

 enclosed in the cocoon before escaping. Then they 

 made an oval aperture in the lower part of the flat- 

 tened end of the cocoon, and escaped through this into 

 the water. 



" One remarkable circumstance was that before 



