MARINE HEMIPTEEA (HALOBATES). 153 



on this surface are a number of long, stiff bristles lying in the shallow groove close to 

 the joint with the proximal tarsal segment. BUCHANAN WHITE drew attention to 

 the curious row of stout, blunt hairs or spines ' on the edge of the inner apical 

 prominence of the shin. In the present species there are more than twenty of these 

 on the male's leg (figs. 5a, 7), and five on the female's (figs. 9a, 10). The arrange- 

 ment of these structures is highly suggestive of a stridulating organ, and it is 

 probable that they form an instrument for rasping along a " comb " formed by a row 

 of sharp, strong spines (figs. 56, 66, 8, 96), about ten in number, and increasing in 

 length as the tip of the shin is approached. This " comb " is situated on the upper 

 face of the apex of the shin. The " file " of each foot must of course play on the 

 " comb " of the other quite a possible arrangement when we remember that the 

 fore legs in these insects are very mobile, and that the feet can be crossed over each 

 other in front of the head. Similar structures occur towards the distal end of the 

 shin in the allied reef-haunting genus Hermatobates (CARPENTER).* 



Male Abdominal Segments. As mentioned above, the present species is 

 characterised by a comparatively slight asymmetry in the " horns " of the 8th 

 segment in the male's abdomen (figs. 13, 14, 15); while the right horn is closely 

 applied to the globose 9th (genital) segment, the left horn is directed laterally 

 outwards at a slight angle. Each horn is expanded at the tip into a falcate process 

 with a few stout black spines (fig. 15). In the allied H. Jlaviventris, ESCHS., the 

 horns are symmetrical, f and each has a somewhat pointed process on the outer 

 margin about the middle of its length, tapering at the tip. It is of interest to 

 remember that H. Jlaviventris, to which the present species is most nearly allied, has 

 been recorded from the Indian Ocean near Ceylon, while H. micans, the species with 

 the very divergent " horn," inhabits all the warmer oceans. It is exceedingly likely 

 that with these insects, as with others, our specific distinctions will become less 

 definite as our knowledge of the possible variations in structure increases. 



Female Abdominal Segments and Ovipositor. It is rather 

 remarkable that while the hindmost segments of the male Halobates have attracted 

 much attention from entomologists, the corresponding region in the female has been 

 neglected. This is probably because, in preserved specimens, the lateral sclerites 

 of the 8th segment (figs. 16, 17, 18, a] are usually in close contact ventrally, and 



* 'Sci. Proc. R. Dublin Soc.' vol. vii., 1891 (plate xii., fig. 6). For descriptions of other stridulating 

 organs in the Hemiptem see HANDLIRSCH, 'Ann. Naturhist. Hofmus. Wien,' vol. xv., 1900, pp. 127-141 ; 

 KIRKALDY, ' Journ. Quekett Micros. Club' (2), vol. viii., 1901, pp. 33-46; and BERGROTH, 'Proc. Zool. 

 Soc.,' vol. ii., 1905, pp. 146-154. 



t BUCHANAN WHITE states (lac. cit., p. 33) that "in 1 all the other species examined [except 

 H. wullerstarffi = micans] both horns are symmetrical," though his figure of H. Jlaviventris from the dorsal 

 aspect (plate ii., fig. 2g) shows the left horn only visible, and slightly divergent as in the present species. 

 NASONOV, however, in his figure of H. flawventru, var. kudrini ('Entomological Researches,' 1893 in 

 Russian Warsaw, 1897, fig. 14), shows the genital segments of the male from beneath, and the two horns 

 appear perfectly symmetrical. 



X 



