120 ZOOLOGISCHE MEDEDEELINGEN — DEEL I. 



It must be noted that the pile of the two last male ventral segments 

 easily comes off and is present in its typical form only in well preserved 

 specimens. The female genital segments in lineatus and Greeni are very 

 much alike, but the differences in the colour-markings of the hemelytra 

 are so constant that also females and carded males in poor condition can 

 be determined without difficulty. 



KB. — Almost all authors have treated the name l/y/^Vo/y/e^v/ as femi- 

 nine, but it is masculine, as Geometra and all other names ending 'm-metra. 



Fam. GERRIDAE. 



1. Gerris fossarum Fabr. 



Banjoewangi (Mc G.). 



In the male the venter (except a median vitta, the lateral margins, 

 and the genital segments) is lead-coloured or fuscous, in the female it is 

 coloured as described by Stâl and Distant. 



Of this species Mr. Jacobson also sent a specimen from Sumatra 

 (Deli, de Bussy). 



Stâl referred this species to Limnogonus, but it certainly belongs to 

 Gerris as limited by Mayr. 



2. Gerris Tristan Kirk. 



Samarang (J.). 



The Javanese G. Ysolt Bredd. is identical with Tristan. Breddin 

 supposed they were distinct because Kirkaldy does not mention the sexual 

 colour-differences of the venter although he possessed both sexes, but his 

 description is faulty and incomplete also in other respects. I have before 

 me numerous specimens of both sexes from the original locality, Kandy 

 in Ceylon, and they show no differences from Javanese specimens. It is 

 a very small and very distinct species, impossible to confound with any 

 other described form, and is widely distributed in southern Asia and its 

 islands. Kirkaldy placed it, with a query, in Limnogonus, but on account 

 of the short antennae and short middle and hind femora it seems to be 

 better placed in Gerris. However, the apical and lateral margins of the 

 sixth female abdominal segment form a very obtuse angle; in this cha- 

 racter it differs from both Gerris and Limnogonus, and a future mono- 

 grapher of the family will possibly find other characters sufficient to 

 establish a new genus upon. Kirdaldy says in his description that the 

 length of the head is " 2 / 5 plus grande que sa largeur", but as a matter 

 of fact the head is distinctly broader than long. He further states that 



