154 HEMIPTERA-HETEROPTERA. 
Twelve winged specimens of this species were obtained in Chiriqui. ‘The males have 
the sixth ventral segment simply emarginate at the apex; two upwardly curved spines 
or hooks, one on each side of the hidden penultimate genital dorsal segment, are visible 
from beneath in this sex, as described by Mayr. In the winged form the pronotum is 
very feebly constricted at the sides, the anterior lobe being completely fused with the 
posterior lobe, without trace of suture. 
POTAMOBATES, n. gen. 
Head subtriangular, produced and declivous in front, angularly dilated on each side above the insertion of the 
antenne; the eyes rather coarsely faceted, large, oblique, somewhat narrowly separated anteriorly, and 
feebly emarginate posteriorly ; rostrum 4-jointed, short, reaching the front of the mesosternum ; antenne 
about half the length of the body, joint 1 nearly as long as the others united, 4 longer than 3, 2 and 3 
separated by a distinct jointlet. Thorax elongate-trapezoidal, gradually widening to the intermediate coxe ; 
the pleura broad and laterally prominent, the propleura rounded externally and extending outwards to at 
least as far as the eyes, the mesopleura still wider; the pronotum in the winged form covering the meso- 
notum, rather narrow, gradually widening to the shoulders and rounded behind ; the mesothorax separated 
from the metathorax by a deep sinuous suture, the metapleura rounded laterally in front and widening to 
the laterally prominent hind cox. Abdomen rather short, with broad, raised connexivum, which is 
slightly produced at the outer apical angle; two genital segments visible above and beneath in the male, 
one in the female; genital segments in the male subcylindrical, the first as long as the two or three 
preceding segments united, the second narrower, both asymmetrically formed; terminal genital dorsal 
segment in the female subtriangular and as long as the preceding segment, the terminal genital ventral 
segment triangular, membranous, and separate, in this sex. Anterior legs short, the coxe widely 
separated; the femora stout, becoming incrassate towards the base; the tibiee curved at the apex, with 
the inner apical angle sharp; the tarsi with the basal joint short, not half the length of the second. 
Intermediate and hind legs very elongate; hind femora thinner and longer than the intermediate femora, 
about one and three-fourths the length of the tibia and tarsus united; second joint of the hind tarsi much 
shorter than the first. Body rarely winged, the mesonotum flattened and shining in the apterous forms. 
This genus forms a connecting link between the freshwater Halobatine forms, 
Platygerris &c., and the normal Gerrids. It differs from Platygerris in the larger 
and more oblique eyes, which are somewhat narrowly separated in front, the much 
longer abdomen, the elongate-trapezoidal mesothorax, with the pleura not distinctly 
separated from the notum, the elongate first genital segment in the male, &c. As in 
Platygerris and various species of Halobates, the genital segments are asymmetrically 
formed in the male. From Gerris and its allies, the present genus differs in the shape 
of the head, eyes, and mesothorax, as well as in the asymmetrical genital segments of 
the male. The two species may be separated thus :— 
Pronotum with a large triangular ochraceous patch on the anterior lobe; 
antenne with joints 2 and 3 subequal in Jength ; first genital segment 
unidentate on the right side at the apex beneath in the 6 . . . . . wmnidentatus, n. sp. 
Pronotum with a narrow ochraceous median line; antennz with joint 2 longer 
than 3; first genital segment bidentate on the right side at the apex in 
the @. . we ee ee ee ew we.) «(Otdentaius, 1. 8p. 
