156 HEMIPTERA-HETEROPTERA, 
the dorsal segments of the abdomen, silvery-pubescent, the pubescence of the under surface paler than the 
ground-colour; the anterior femora with a few bristly hairs at the base in front. Antenne with joint 1 
nearly as long as 2-4 united, 2 and 4 subequal in Jength, 3 considerably shorter. Pronotum short, 
transverse, depressed in the centre. Mesonotum about two and one-half times the length of the pronotum 
finely canaliculate down the centre behind, the channel continued on the metanotum. Propleura extending 
outwards to beyond the eyes. Mesopleura very broad throughout, gradually widening to the intermediate 
coxe. Anterior femora very stout, becoming strongly incrassate towards the base. Sixth connexival 
segment rounded at the outer apical angle. T'erminal ventral segment transversely depressed beyond the 
middle, the apex broadly arcuate-emarginate, the apical margin ciliate. First genital segment without 
sulcus at the base beneath, as long above as the three preceding segments united, the lower apical margin 
produced on the right side into two prominent somewhat widely separated teeth. Second genital segment 
with a long projecting process, which is subtriangularly dilated at the apex, at the base on the right side 
beneath. 
Length 11, breadth 3, millim. 
Hab. Mexico (Sallé, in Mus. Holm.). 
One example. Larger and more robust than the male of the apterous form of 
P. unidentatus, with the meso- and metanotum immaculate, the anterior lobe of the 
pronotum broader and with a narrow flavescent median line, the second antennal 
joint more elongate, the anterior femora stouter, the first genital segment longer and 
bidendate at the apex beneath, &c. The long chitinous process arising from the base 
of the terminal segment on the right side (from the left side as seen from above) is 
visible between the two teeth ; it is abruptly truncate at the apex. 
PLATYGERRIS. 
Platygerris, Buchanan White, Ent. Monthly Mag. xx. p. 36 (1883). 
The apterous Mexican insect referred to this genus has been described at great length 
by Buchanan White. A second species, from Costa Rica, of which we possess a winged 
example, is now added. ‘They live upon the surface of fresh water. 
1. Platygerris depressus. (Tab. IX. figg. 23,3; 24, apex of the abdomen 
from above, 2; 24 a, ditto, from behind.) 
Platygerris depressa, Buch. White, loc. cit. pp. 36-89 (¢)’. 
Hab. Mexico (Mus. Berol.!: 3), Teapa in Tabasco (7. H. Smith: 3 @ ). 
Two pairs of this species have been received from Teapa. The females have the 
apex of the last ventral segment subtriangularly produced in the middle and furnished 
on each side with a rather long narrow lobe, these being conspicuous from above; the 
first genital ventral segment is vertical and fissured to the base, the apex of the abdomen 
appearing abruptly truncate. The insect is described as black, but the specimens before 
me, including one of the types, have a bluish or eneous lustre above. 
Buchanan White, in describing the form of the genital segments of the male, assumed 
that they were distorted in drying; but this is not the case, the armature being asym- 
metrical, as in various other species of the group: the first genital ventral segment * is 
* The second segment of Buchanan White, his first genital segment being here regarded as the terminal 
ventral. 
