AQUATIC HETEROPTERA. 



73 



stoutest and slightly curved near base ; second and third segments equal in 

 length ; fourth a little longer than first or subequal to it. Hind margin of last 

 (sixth) abdominal sternite roundly sinuate, forming an arc, genital segments 

 much rounded at the apex (see text-fig. 3). 



Similar to male, but much larger. Fourth segment of antennae some- 

 times slightly shorter than, generally subequal to first segment in length. Last 

 (sixth) abdominal sternite truncate at apex, without tooth-like process. 



Text-fig. 4. — Limnogonus hopkinsi Esaki, sp. n. a, antenna • h, (J genital segments, ventral 



view ; c, the same of 



Length of body : (J 4 mm., $ 6 mm. , breadth of body : (^1-3 mm., $ 2 mm. 



Upolu : Apia, type type 3 paratypes and 1 $ paratype, 5.vi.l924 ; 

 Vailima, 1 ^, 1 $, 20.iii.l925. 



This interesting species is unlike any other known member of the genus 

 Limnogonus owing to the striking difference in size between the sexes, the shape 

 of the last abdominal and genital segments, and the considerable length of the 

 last antennal segment, which is the longest of all in the male. With the excep- 

 tion of some oceanic forms, the sexual difference in size is not so striking in other 

 members of the (rerm-group. Limnogonus hopkinsi. sp. n., described below — a 

 much larger species — exhibits a similar sexual dimorphism in the matter of size. 



5. Limnogonus hopkinsi, sp. n. Text-fig. 4. 

 (^$. Apparently very similar to the foregoing species, except in size. The 

 description of the colour and markings of L. buxtoni Esaki will serve also for 

 the present species. The of this species is about as large as the $ of L. buxtoni, 



