HALOBATES. 153 



" Length rf 3-5, breadth 2, middle femur 4, hind femur (?) millim. 

 $3, 2-25, 4, 3 millim." 



Hob. Andaman Sea. " Tithal, Bulsar, Bombay." North Pacific 

 Ocean and Celebes Sea (Challenger}. China Sea (Gigliolijide 

 Buchanan White). 



Buchanan White remarks : " This species might readily be 

 mistaken for H. sericeus, Esch. (a widely distributed species), from 

 which, however, it seems to be structurally distinct." 



2927. Halobates herdmani, Cat-pent. Eept. Pearl Oyster Fisheries, 

 pt. 5, p. 151, pi. v, figs. 1-19 (1906). 



" Feeler with 4th segment half as long again as 3rd, slightly 

 shorter than 2nd. Fore foot with the two tarsal segments sub- 

 equal. Intermediate foot with the proximal tarsal segment two 

 and a half times as long as the distal. Abdomen of male with the 

 8th segment slightly asymmetrical, the ' horns ' being both inclined 

 towards the left, so that while the right horn is closely applied to 

 the 9th segment, the left is somewhat divergent from the axis of 

 the body ; both horns are falcate at the tip. 



"This species is most nearly allied to H. flaviventris, Esch. 

 [vol. ii, p. 188], of all members of the genus hitherto described. 

 It differs from that species principally in the shape and in the 

 slight asymmetry of the ' horns ' of the 8th abdominal segment of 

 the male. The form of this segment in the present insect shows 

 an interesting stage of transition between the symmetrical 

 condition found in the great majority of the species of Halobates 

 and the excessive irregularity of H. micans, Esch. [vol. ii, p. 187} 

 in which the left horn of the segment projects almost at right 

 angles to the axis of the body. 



" In colour H. herdmani resembles the other species of the 

 genus. The dorsal and lateral surfaces appear deep blue-black 

 when wet, and ashy grey (owing to the deep pubescence) when 

 dry. On the head is the usual pair of orange triangular marks, 

 while the feelers and legs are black. The thoracic sternum is dark 

 centrally showing only two pale elongate patches towards the 

 lateral sutures close to the bases of the hind legs. The abdominal 

 sterna are mostly pale, but they appear dark laterally and along 

 their hinder borders ; the 1st abdominal segment, on which is the 

 opening of the repugnatorial glands, is deep brown." (Carpenter.) 



" Length, tf 5-2, $ 5-7 millim." 



Hob. Indian Ocean near Ceylon (Herdman, Brit. Mus. ; Bain- 

 brigge-Fletcher, Brit. Mus. $ Coll. Dist.). 



The type of this species is in the collection of the British 

 Museum. 



