AQUATIC HETEROPTERA. 



69 



Length, of body : 1-6 mm., $ 1-7 mm. ; breadth of body ; 0-6 mm., 

 $ 0-7 mm. 



Upolii : MuHfanua, type type 2 paratypes, x.1925, in marsh. 



This species is smaller than Microvelia prompta Cheesman and larger than 

 M. oceanica Distant.* From the former M. samoana Esaki differs also in the 

 stouter shape of the body and the much narrower connexivum. From the 

 latter it differs in the ratio of the antennal segments. 



GEERIDAE. 

 Llmnogonus Stal. 



Three closely allied species of this genus occur in the Pacific Islands. These 



are : 



Limnogonus fossarum (Fabricius), type locality, E. India. 



Limnogonus discolor (Stal), type locality, Tahiti. 



Limnogonus luctuosus (Montrouzier), type locality. New Caledonia. 



Limnogonus nymphae (Esaki), of Formosa, can be synonymised with L. 

 fossarum (Fabricius), and L. lineatus (Carpenter), of Murray Island, may be 

 synonymous with L. discolor (Stal). The type ((^) of L. lineatus (Carpenter) 

 is in the British Museum ; with that exception I have not yet had the oppor- 



* Hale {Records S. Austr. Mus., Adelaide, iii, p. 208, 1926) identified an Australian Microvelia 

 as M. oceanica, but liis species is quite distinct from ill. oceanica Distant, and is apparently new. 

 It may be characterised as follows : 



Microvelia halei, sp. n. 



Differing from Microvelia oceanica Distant in the following characters : 

 Larger size : Length of body in apterous form " 1-66 mm. to 2 mm.,"' while in the apterous 

 form of M. oceanica, the body measures 1-51 mm. in the ^, and 1-65 mm. in the These measure- 

 ments were made from the cotypes of M. oceanica Distant in the British Museum. Distant's 

 original description (Sarasin and Roux, Nova Caledonia, Zool., i, pt. 4, no. 10, p. 383, 1914) was 

 based only on the winged form, which measures "2 mm.," though the author gave figures of 

 both forms. 



Different ratio of the antennal segments : Hale describes the antennae of M. oceanica Hale, 

 nec Distant, as follows : " first segment nearly one-fourth longer than second, subequal in length 

 to third and about three-fifths as long as fourth, which is more than twice as long as the second." 

 In the true M. oceanica the ratio is 10 : 8 : 10 : 21 and 11 : 9 : 11 : 23 in (J and $ respectively. 

 Thus in the latter species the last segment is considerably longer, in comparison with the other 

 segments, than in M. halei, in which it is much less than twice the length of the third segment. 

 Reference should be made to the full description and figures given by Hale {loc. cit.). 



