140 HEMIPTERA-HETEROPTERA. 
The insect was found on the surface of freshwater streams in the Isla del Rey, the 
largest of the Pearl Islands. 
TROCHOPUS. 
Trochopus, Carpenter, Ent. Monthly Mag. xxxiv. p. 78, t. 3 (April 1898). 
The type of this genus is 7. plumbeus (Uhler) (= marinus, Carp.), from the Antilles 
and Florida, and the species from the Pearl Islands now added is an allied form. It 
differs chiefly from Rhagovelia in having the tarsi 3-, 2-, 2-jointed, the very small basal 
joint of the intermediate pair being obsolete, and the second and third joints of the 
hind pair fused into one. The two species are constantly apterous, and have the 
pronotum reduced to a short lobe, the larger portion of the disc of the thorax being 
occupied by the mesonotum. 
The beautiful structure of the intermediate tarsi has been figured by Mr. Carpenter 
(loc. cit.). The males have a row of short teeth on the inner edge of the posterior 
tibie, that of 7. salinus having, in addition, a long tooth on the anterior trochanters. 
It is probable that, as in the pelagic Halobates, &c., wings would be of very little use 
to these insects, the water upon which they live never drying up; whereas in the fresh- 
water [thagoveliw, which have occasionally to migrate when the streams dry up, wings 
are a necessity, at least in a certain number of individuals of each species. 
Both insects live gregariously on the surface of salt-water in sheltered creeks 
and inlets. 
1. Trochopus salinus, n. sp. (Tab. IX. figg. 4, ¢, from beneath; 5, 2, from 
above. ) 
Ovate (2 ), subfusiform ( ¢ ), black or brownish-black, mottled with grey, beneath entirely grey, the pronotum, 
except at the sides, the connexival margins broadly, and the apex of the abdomen more or less, above and 
beneath, ferruginous ; the antenne brownish-black, with the basal half or more of the first joint flavous 
or ferruginous; the legs brownish-black, the anterior and hind femora in great part, and the intermediate 
femora at the base, ferruginous or flavo-ferruginous; the coxe and trochanters flavous; the upper surface 
thickly clothed with pale brownish pubescence, the head, pronotum, and pleura also with bristly hairs, the 
under surface with greyish pubescence; the antenne and legs thickly pubescent, and also clothed (the 
two outer joints of the antennz excepted) with long fine hairs and a few sete. Head with a smooth 
impressed median line; antenne long and slender, joint 1 twice as long as 2, 2 and 4 subequal in length, 
3 considerably longer, 4 fusiform, 2 and 3 separated by a distinct jointlet. Pronotum separated from the 
mesonotum by a deep transverse suture, the mesonotum slightly sinuate behind. Connexivum raised and 
broadly expanded. Legs long and rather stout, the intermediate pair very long, with the penultimate 
tarsal joint much longer than the apical one. 
6. Anterior trochanters armed with a long, acute, outwardly-directed tooth ; posterior femora slightly incras- 
sate, armed with a row of minute teeth, and with a longer and rather prominent tooth at the middle. 
@. Posterior femora feebly incrassate, unarmed, or, at most, with one or two minute teeth about the middle. 
Length 31-34, breadth 12-14 millim. 
Hab. Panama, San Miguel in the Pearl Islands (Champion). 
Found in abundance in small creeks reached by the tide, in the mangrove swamps of 
the Isla del Rey, or San Miguel, the largest of the Pearl Islands. 
