22, 4 Esaki: New Water Strider from Formosa 389 



than second in male, and the former almost twice as long as the 

 latter in the female; claws inserted before apex of tarsi. Inter- 

 mediate and posterior coxae, trochanters, and basal one-third of 

 femora brown ; rest of femora, tibiae, and tarsi black ; interme- 

 diate and posterior femora about subequal in length, very long 

 and slender, the former being about twice as long as the inter- 

 mediate tibiae and the latter about three times the length of the 

 corresponding ones ; intermediate tibiae with a fine fringe of long 

 hairs, though somewhat indistinct in the dried specimens ; tarsi 

 very much thinner than tibiae, without claws ; first intermediate 

 tarsal joint about eight times as long as second; posterior tarsi 

 very short, second joint slightly longer than first. 



Abdomen in male somewhat shining black above; apex of 

 genital segment and below brown, the latter somewhat silvery 

 pubescent; in the female the end of abdomen turns upward 

 markedly, the morphological dorsal side scarcely visible, as the 

 ventrolateral sides roll up considerably. The apparent dorsal 

 side except anal segment black with silver pubescence, ventral 

 side and anal segment pale brown with similar pubescence ; anal 

 segment thin walled, forming a tubelike structure, its upper 

 margin black and the lateral sides pointed posteriorly. Length 

 of body, male, 6.5 millimeters ; female, 9.5. 



Holotype, female, 1 captured at Sosan near Taihoku on Sep- 

 tember 25, 1921, by T. Esaki, allotopotype, male, paratopotypes, 

 and paraidiotypes from Shinten near Taihoku are all in my 

 collection. There are also two specimens from Kusukusu near 

 Koshun in the collection of the section of applied zoology, De- 

 partment of Agriculture, Government Research Institute of For- 

 mosa in Taihoku. 



This species is named in honor of my friend Mr. R. Taka- 

 hashi, to whom I acknowledge indebtedness for many favors. 



This curious water strider was found at first on a very rapid 

 stream in a rocky ravine at Sozan. The insects glide swiftly 

 on the surface of the water in all directions and are hardly 

 recognizable owing to the disturbance of the water. They look, 

 however, somewhat like whirligig beetles. Some of them were 

 found climbing on the rocks near by. Numbers of specimens 

 in copula were also captured. Numerous examples were found 

 on the Shinten River which is a very much larger stream than 



