A New Cricket of aqaatic habits found in Fiji. 283 



peculiar structure in the leg. Even the common house- 

 cricket, though nearly twice as long as the aquatic cricket 

 from Fiji, and many times heavier, does not sirdc in water, 

 and can propel itself awkwardly upon the surface, though 

 it cannot leap upon it. 



It is well known that another genus of cricket (Tindac- 

 tylus, placed by Saus.sure in the tribe of Gryllotalpida?) 

 is capable of leaping on water. Here the hiad tibia bears 

 two rows of articulated and flattened plates, four on one 

 side and three on the other. From the extremity of the 

 joint project two pairs of spurs and the rudimentary 

 tarsus. Tridactylus differs so conspicuously from other 

 crickets in the antennae and wings that it cannot be 

 supposed to be nearly related to our cricket, and the 

 similarity in the liind tibia is no doubt purely adaptive.* 

 In Scelymena, Serv., a genus of Tettigida^, of which 

 rcveral species occur in Ceylon, Java and Burmah, the 

 hind tibia ends in four strong, articulated spines, and the 

 first tarsal joint may be dilated. Tliese insects live on 

 the margins of streams and ponds ; some of them have 

 been seen to leap on water.f Dr. Brunner von Wattenwyl 

 tells us that several groups of Phasmidse are known to 

 him as possessing the same power. The long hairy 

 spines of Pseudoiiemobius pictus (Gryllidte) from Cashmere 

 suggest that this insect also may leap upon water, but 

 its habits have not been described. Certain Hemiptera, 

 such as Gerris (Hydrometra) lacustris, and some Collem- 

 bola, such as Podura aquatica and Isotoma palustris, can 

 also leap upon water, a faculty which becomes less re- 

 markable as the size of the insect diminishes. The Fijian 

 cricket attains a length of 11 m.m., Tridactylus variegatus 

 6 m.m., Gerris lacustris 9 m.m., while neither of the 

 Collembola exceeds 2 m.m. 



The female insect differs most conspicuously from the 

 male in the presence of a rather long, curved ovipositor, 

 and in the quite different pattern of the wing-cover. The 

 ovipositor resembles that of some other Trigonididaj.J 



The larva has no wings, no ovipositor, no auditory 



* The mode of life of Tridactylus is carefully described by 

 Saussure, Reelierches, VI, pp. 321-3. 



t Saus.sure, Etudes sur quelques Orthoptei'es da Musee de Geneve ; 

 Ann. Soc. Ent. Fr., 4" ser., toni. I, pp. 467-494 (1861). 



X Saussure, Melanges OrUiopt., torn. II, pp. 522-531, and Fig. 



