BRITISH WATERBUGS. 155 



though seemingly content with Daplinia or Cyclops, among the 

 Entomostraca. Although in a " hand-to-hand " fight they would 

 stand no chance with the fierce Notonecta, yet such is the grip 

 of their raptorial front legs, that an unlucky water-boatman 

 venturing heedlesslj'- within range of the stroke of the silent 

 scorpion will be seized and sucked without being able to struggle 

 successfully, or use his powerful beak to advantage. The 

 Nepidae also suck fishes' eggs, and even attack small fish and 

 tadpoles. 



Owing to their remarkable shapes, the Nepidae were favourite 

 objects of study with the older naturalists, and their structures and 

 life-histories have often been sketched superficially, though precise 

 descriptions and figures are still desiderata. Their anatomy and 

 embryology have been dealt with by such workers as Dufour, 

 Heymons, Korschelt and Heider, Locy, Lacaze-Duthiers, J. 

 Martin, Marshall and Severin, Schmidt and Will. Bachmetjer 

 (1900, Illustr. Zeit. Ent. v. 88) quotes Pouchet that Ilanatra, 

 Nepa, and Notonecta can sustain life for three hours at a tem- 

 perature of —16° C. 



Like the other waterbugs, the Nepidse are subject to the 

 attentions of larval Hydrachnidje. 



There are two genera of Nepidae in Britain, easily recognized 

 by their shape ; each has a single British species. 



1. Flat, broad . . . . Nepa cinerea, Linne. 



2. Elongate, subcylindric . . Eanatra linearis (Fabricius). 



Nepa cinerea, Linne.* 



This is the NejM scorpw-aqaaticus of De Geer. The prevail- 

 ing colouring is dirty brown, but when the tegmina and wings 

 are spread the greater part of the tergites is seen to be bright 

 red. 



Handlirsch declares that Swinton's diagrams of the stridular 

 organs in this genus are false, and that Nepa does not stridulate. 

 As Eanatra, however, has recently been discovered by my friend 

 Bueno to stridulate, it is probable that Nepa does also, though 

 both Swinton and Handlirsch have overlooked the proper appa- 

 ratus. 



The earliest representation of iV6/;a known to me is in Moufet's 

 * Insectorum sive minimorum Animalium Theatrum,' p. 321 

 (1634), where three recognizable figures of *' Scorpio palustris " 

 are shown ; the third, while representing a nymph, indicates 

 tegmina, the details having probably been filled in from an 

 imago. Frisch, in 1728, in his work above mentioned (vii. 



* Latin nepa, a scorpion ; it was also used by Cicero to denote the con- 

 stellation of the same name, but Plautus employed it to denote the con- 

 stellation " Cancer." Geoffroy, following Schaeffer, arbitrarily altered it 

 to Hepa. 



