REPORT ON THE PELAGIC HEMIPTERA. 57 



below with fine spines ; tibia with spines all round ; tarsus less than one-fourth the 

 length of tibia, cleft at about two-thirds of the length. 



Abdomen : sixth ventral segment a little longer than the preceding ones, hind margin 

 straisfht. 



Genital segments : first below as long as all the ventral abdominal segments together, 

 disk slightly convex, hind margin straight, sides oblique ; second with horns reaching 

 three-fourths the length of the third below ; near the base of each horn, and exterior 

 to it, is a conspicuous obtuse tubercle. Third above (PI. II. fig. 2, g.) with the lateral 

 angles acuminately produced. 



This seems to be a scarce species. Eschscholtz saw the male only (which he calls the 

 female). I have seen two specimens, both males. The female has not been discovered. 

 The Oxford Museum specimen was captured on September 12, 1834. 



11. Ilalohates frauenfeldanus (PI. 11. fig. 3). 



Halobates Jtaviventris, Frauenfekl (iieo Eschscholtz), Verhandl. der k. k. zool.-bot. Gesellsch. 

 in Wien, vol. xvii. p. 459, Taf. sii. figs. 3, 4, 7, and 9, 1867. 



Oval, widest behind the middle ( ? ). Pale hoary ash grey above. Head with a 

 brownish-yellow spot on each side posteriorly, united to a narrow line of the same colour 

 on the hind margin. Antennae with the basal halves of the joints ; prosternum ; meso- 

 sternum with a central longitudinal line broadest behind and narrower in front (absent in 

 the $ ) ; ventral segments of the abdomen ; a spot near the insertion of each of the legs ; 

 the front femora below, and a more or less extensive spot at the base above, as well as 

 the under side of the coxas of the middle and hind legs, yellow. Front femora black 

 above. Antennae : second, thii'd, and fourth joints equal in length. Front tarsus with 

 first joint about one-third shorter than the second joint. Middle tarsus with first joint 

 two and one-half times the length of the second. 



$ . Length 4*1, breadth 1'9, middle femur 5'1 mm. 



$ . Length 4'2, breadth 2"4, middle femur 5 mm. 



Habitat. — Indian Ocean near the Nicobar Islands (Frauenfeld). 



I have not seen this species, and have compiled the diagnosis and description from 

 Frauenfeld's paper. The latter author's description is a little confusing, as he sometimes 

 uses the sign $ (both in the text and in the plate) when he evidently intended to write 

 $ . He has made the same mistake as to the sex as Eschscholtz and other writers 

 have done. Moreover, he gives two difiierent measurements for the female (his male). 

 Frauenfeld's description applies chiefly to the female, for, as he thought, the male had 

 already been described by Eschscholtz. I am indebted to Dr. Rogenhofer for measure- 

 ments of the front and middle tarsi of specimens in the Vienna Museum. 



(7,nOL. CHALL. EXP. — r.lRT XIX.-- 1883.) T S 



