152 " HEMIPTERA-HETEROPTERA. 
facies, due to their shining head and pronotum; they have, moreover, a rather short 
basal joint to the anterior tarsi, this character separating them from Limnometra. 
The pronotum in the winged forms is subtriangularly produced behind. 
Two species from the Amazons were doubtfully included in Limnogonus by Buchanan 
White. The Central-American forms may be differentiated thus :— 
Pronotum distinctly carinate; sixth connexival segment pointed at the outer 
apical angle in the ?; first genital segment simple in the ¢. . . . . marginatus, Guér. 
Pronotum. not carinate; sixth connexival segment acutely produced at the : 
outer apical angle in the $; first genital segment acutely produced 
beneathinthe 9. . 1. 1 ee ee ee ee we ww eee) Ayalinus, Fabr. 
1. Limnogonus marginatus. 
Gerris marginatus, Guér. Icon. Régne Anim., Ins. p. 351, t. 57. fig. 2°; in Ramon de la Sagra’s Hist. 
fis., polit. y nat. de Cuba, Ins. p. 173’. | 
Limnometra marginata, Uhler, P. Z. 8. 1893, p. 706°; 1894, p. 212°. 
Gerris guerini, Leth. et Sev. Cat. gén. Hémipt. Hétéropt. p. 61°. 
’ 
Winged form. Rather slender; the head and pronotum shining, black, the head with two longitudinal lines, 
united posteriorly, and the sides behind, ochraceous ; the pronotum with the lateral and posterior margins 
narrowly, two short lines on the anterior lobe, and a narrow median line extending thence to near the 
apex, becoming indistinct behind, flavous or ochraceous; the elytra blackish-brown, streaked with pale 
brown on their inner half (much paler when opened); the wings white and iridescent ; the body beneath 
and the pleura ochraceous, the pleura broadly striped with black, the venter with a row of dark spots or 
an evanescent black line on each side; the abdomen above ochraceous, striped with black; the antenne 
and legs fuscous or blackish, the anterior femora paler at the base; above sparsely clothed with very 
short fine brownish pubescence; the under surface and pleura thickly clothed with silvery pubescence. 
Antennz about reaching the hind coxs, slender, joint 1 slightly longer than 4, 2 and 3 subequal in length, 
each shorter than 4. Pronotum with a distinct median ridge anteriorly, the posterior margin thickened, 
the anterior lobe distinctly defined. Elytra with prominent nervures. Mesopleura moderately dilated 
before the intermediate cox. Sixth connexival segment pointed at the outer apical angle. Mesosternum 
~ eanaliculate anteriorly. Legs slender; anterior femora and tibie almost straight, the femora a little 
thickened ; anterior tarsi with joint 1 much shorter than 2; posterior femora nearly one-half longer 
than the tibia and tarsus united, the first tarsal joint almost twico as long as the second. 
6. Anterior femora stouter and slightly curved; anterior tibiee feebly curved, sinuous within ; 3 sixth ventral 
segment simply arcuate-emarginate at the apex ; first genital segment not produced at the middle of the 
apical margin beneath. . 
Length 7-73, breadth 12 g-14 millim. (d 2.) 
Hab. Mexico, Teapa in Tabasco (4. H. Smith) ; Brivise Hownpouras, Belize 
(Blancancaus). —ANTILLES, Cuba ?? 5 St. Vincent ®, 3, Grenada 4. | 
Of this species: we have obtained: three specimens from C entral America, all females. 
They are smaller and narrower, and have more slender legs, than most of the examples 
I have seen from the Antilles; the latter, however, vary greatly in size. 
As there may be some doubt as to whether this or the. following closely allied 
species is really referable‘to Z. marginatus, a full description is given from the Central- 
American.females before me ;.. the male-characters .are taken from the Grenada and 
