TROPISTERNUS.—OOCYCLUS. 61 
This species is of shorter form and more attenuate behind than its allies here 
described, and is readily distinguished by this and the characters above mentioned. 
The series of about two dozen individuals shows very little variation. ‘The specimens are 
in very decayed condition; so that the colour of the legs perhaps appears more obscure 
and concolorous than is natural. Although resembling 7. tinctus in the absence of 
sculpture and spines from the marginal border of the wing-cases, 7. odscurus is 
nevertheless quite different in colour, form, and appearance, and possesses a structure 
of the epipleura which is peculiar to it: if the wing-cases be opened so that the inflexed 
epipleura can be seen, it will be observed that, although very broad at the base, it ceases 
or thins away about the middle; whereas in 7. tinctus and other species it continues 
broad beyond the middle, although it is completely folded in and applied to the inner 
face of the wing-case. 
HYDROCHARIS. 
Hydrochare, Latreille, Fam. Nat. p. 366. 
Hydrophilus, Leach, Zool. Mise. iii. p. 94. 
Hydrous, Brullé, Hist. Nat. Col. 11. p. 275. 
This genus has a very wide distribution in the two hemispheres, and comprises about 
twenty described species. 
1. Hydrocharis perfectus. (Tab. II. fig. 8.) 
Oblongo-ovalis, parum convexus, nitidus, niger; pedibus piceis, antennarum basi palpisque testaceis ; elytris 
subtiliter seriatim punctatis, nullomodo striatis; prosterno in medio anterius parum producto, obtuso, 
posterius angulum acutissimum formante, sed vix Spinoso. 
Long. 18, lat. 74 millim. 
Hab. Guatemata, Torola 1000 feet (Champion). 
Palpi very elongate. Antenne with the sixth joint forming a very elongate spoon, 
seventh elongate and with long ramose process. Head rather finely and not densely 
punctate, and with the larger punctures on the clypeus numerous. Thorax finely 
punctate, its anterior angles rounded and very little produced. Elytra with four 
isolated series of punctures, but without any striz near these, also with punctures near 
the sides, the surface generally only obsoletely punctate. Posterior femora quite 
impunctate beneath. Apical ventral segment with quite narrow shining space at the 
extremity. 
OOCYCLUS. 
Caput subhemisphexricum. Antenne perbreves, 8-articulate, articulis tribus ultimis abrupte majoribus, 
clavam laxam formantibus. Palpi maxillares perbreves, articulo ultimo quam precedens paulo longiore. 
Mesosternum ante coxas intermedias in processum magnum scabrosum elevatum. Metasternum subtilissime 
pubescens. Abdomen e segmentis quinque compositum, nitidum, crebre setosum. Femora subtus nitida. 
Tarsi posteriores tenues, lineares, tibiis multo breviores, 5-articulati, articulo basali quam secundus multo 
breviore. 
I propose this genus for some peculiar Palpicorns allied to Hydrobius, but differing 
