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XVI. Oil a new cricket of aquatic habits, found in Fiji hi/ 

 Professor Guslave Gilson. By Professor Louis 

 CoMPTON Ml ALL, F.R.S., and Professor Gustave 

 Gilson. 



[Read May 7th, 1902.] 



Plates VTI and VIIL 



The aquatic cricket now to bo described was obtained by 

 Professor Gilson of Louvain in Viti-Levu, Fiji, on October 

 23rd, 1897. It was found on a branch of tlie Upper Navua 

 river, a clear and rapid stream, flowing tlirougb a deep, 

 rocky valley. Myriads of black specks were seen dancing 

 on the surface of the water. When alarmed, they hid 

 bcliiud stones. They skated on the water, or jumped to a 

 height of about six inclies, usually several times in close 

 succession, and were sometimes seen to leap upon very 

 disturbed water. Now and then three or four^ of the 

 crickets seemed to be playing at leap-frog, and jumping 

 over one another, as if in sport. They were very hard to 

 catch, though several men were employed in capturing 

 them, and very few specimens were secured. Night 

 interrupted the work, and next day an attack of malarial 

 fever obliged Professor Gilson to desist. Rainy weather 

 followed, the river rose, and no more was seen of the 

 crickets. 



The largest male specimen was 11 m.m. long, not 

 including the antennae, cerci, or wing-tips. In most 

 respects the head resembles that of other Gryllidas.^ The 

 mandibles exhibit a peculiar structure, the masticatory 

 surface consisting of three cutting ridges, alternating with 

 molar surfaces, which are armed with close-set denticles 

 (fig. 8). No ocelli were found. A pair of cerci project 

 from the 7 th abdominal segment. 



The wing-covers of the male have the dorsal area 

 largely membranous ; the general arrangement of the 

 veins is somewhat like that of the Gryllidae in which the 

 male stridulates, and altogether different from the vena- 

 tion of the female wing-cover. The roughened file, the 

 chanterelle, the chords and the oblique veins are either 



trans, ent. soc. lond. 1902. — part hi. (no v.) 



