112 
Psyche 
[April , 
ON THE GENUS HALOBATES FROM JAPANESE AND 
FORMOSAN COASTS (HEMIPTERA: GERRID^). 
By Teiso Esaki. 
Entomological Laboratory, Department of Agriculture, Kiushiu 
Imperial University, Fukuoka, Japan. 
Of that well known pelagic genus of Hemiptera, Halobates, 
only two species have hitherto been recorded from the seas 
adjacent to Japanese islands. Recently, four more species, all 
apparently new, have come under my observation, thus giving 
in all six species to the Halobates-fauna of the same region. 
Before describing these new species, it may be pointed out 
that the hind tarsus of this genus is two-jointed, instead of being 
one-jointed. The alleged one-jointedness of the hind tarsus has 
been considered as an important generic character of Halobates 
by many entomologists, except Dahl, who states that “Die Tarsen 
sind ebenfalls zweigliedrig” (Plank. Exped., Humboldt-Stiftung, 
Bd. 2, p. 2, 1893). The hind tarsi of all the species studied by me 
are two-jointed, as in all the other genera of the Family Gerridse. 
This point is often difficult to make out, because of the fact that 
the joints are extremely slender and pubescent. In newly 
moulted specimens, however, the two-jointedness is readily 
recognizable. 
Halobates apicalis sp. nov. (Fig. A). 
Body ashy gray. Head pale yellowish brown, with a prominent 
longitudinal fascia on the vertex; frons with a black spot which 
is sometimes confluent with the fascia on the vertex. Eye 
moderately projected laterally, dark brown. Antenna with two 
basal joints pale yellowish brown and two apical joints black; 
first joint longer and thicker than others, with two blackish 
brown lines beneath; second joint about two-thirds as long as 
the first; fourth joint slightly shorter than the second, tapering 
toward the apex; jointlet between second and third joints pale 
