ADAPTATIONS TO HAUNTS AND SEASONS 297 



cling to a dead jelly-fish and suck its juices. Of their 

 movements Walker writes : *' In tropical latitudes when a 

 sailing ship is becalmed or a steamer stopped in a perfectly 

 calm sea, it is not long before little whitish creatures are 

 seen rapidly skimming over the glassy surface with a sinuous 

 motion. ... A heavy swell, provided the weather is calm, 

 does not prevent their appearance, but with the ripple 

 caused by the slightest breeze they vanish at once. . . . 

 Sometimes they were to be found in plenty on the narrow 

 belt of smooth \vater to leeward of the ship when not one 

 was to be seen on the windw^ard side." The behaviour of 

 captured specimens in a vessel of sea-water was watched. 

 " On the approach of the finger or a pencil they dive readily 

 and swim with great facility beneath the surface, the air 

 entangled in the pubescence giving them a beautiful appear- 

 ance like that of a globule of mercury or poHshed silver. 

 This supply of air must be essential to the existence of the 

 insects which must pass a large part of their Hfe beneath 

 the surface of the sea diving into undisturbed water in rough 

 or even in moderate weather, and coming up again only 

 when it is absolutely calm." But little is known about 

 their breeding habits. Their reddish eggs are large as 

 compared with the size of the mother, who may carry tw^o 

 or three about attached to the underside of her body. The 

 floating feather of a sea-bird picked up in the Pacific Ocean 

 off the Galapagos was found to be covered with masses of 

 Halobates' eggs surrounded by a gelatinous envelope. 

 H. C. Delsman (1926) has lately recorded the presence of 

 thousands of the eggs on various objects floating in the 

 Java Sea — seaweeds, Spirula and Sepia shells, wood and 

 cork, in addition to feathers, yet only twenty-five eggs 

 have been detected at once" in the body of a single female. 

 Doubtless many females lay their eggs on one convenient 

 floating nest, for these wonderful little insects are gregarious 

 in their manner of life. Of other marine Hemiptera 

 mention can only be made of the minute but heavily built 

 Hermatobates, with hairy body, very stout fore-legs, and 

 abdomen still more reduced than Halobates, so that the 



