64 HYDROPHILIDZA. 
sides rather more distinct. Elytra of a dark brassy colour, with rather numerous spots 
of a delicate green colour ; they are without a sutural stria, and are sparingly and rather 
finely punctate. | 
The only individual sent by Mr. Champion of this species is in a fragile condition, 
but seems to be closely allied in structure to O. brevicornis; the abbreviation of the 
palpi is extreme; the prosternum is only very finely carinate, and the two spines with 
which it is armed in front are quite minute; the front coxe are destitute of spines. 
HYDROBIUS. 
Hydrobius, Leach, Zool. Mise. ii. 1817, p. 92. 
Considerable discrepancy of opinion exists as to the extension to be allowed to this 
genus, many authors (probably with reason) separating from it the genera Paracymus 
and Anacena of C. J. Thomson. I have, however, decided here, merely as a matter of 
temporary convenience, to use the generic name in its wider sense, as is done in the 
Munich Catalogue of Coleoptera. As thus understood it consists at present of some 
forty or fifty species distributed in most of the temperate parts of the world, but scarcely 
entering the tropics. I here register three species under the name, all of them belonging 
to the group or subgenus Paracymus. 
1. Hydrobius subcupreus. 
Hydrophilus subcupreus, Say, Journ. Acad. Phil. v. p. 189°. 
Hydrobius subcupreus, Lec. Proc. Ac. Phil. 1855, p. 373°; Horn, Tr. Am. Phil. Soc. xiii. p. 185°. 
Hab. Nortu America ?, from Canada and Oregon southwards.—MeExico, Guanajuato 
(Dugeés, coll. Sallé); GuatemMata, Duefias and Guatemala city, Paso Antonio, Quiche 
Mountains 7000 to 9000 feet (Champion); Nicaragua, Chontales (Janson). 
The specimens before me show much variation in size; but I have not been able to 
find any satisfactory character of specific distinction ; the individuals from Chontales 
and Paso Antonio form, however, a well-marked variety, characterized by very small 
size and more finely punctate upper surface. The front, or free angle, of the mesosternal 
lamina projects downwards in this species as a sort of tooth or spine. 
2. Hydrobius armatus. 
Oblongus, sat convexus, supra enescens, nitidus; antennarum basi palpisque testaceis, his apice leviter infuscato ; 
prothoracis lateribus anguste, elytrorum apice late flavescentibus; pedibus rufo-testaceis, elytris parce 
obsolete punctatis. 
Long. 1, lat. 3 lin. 
Hab. Guatemata, Duefias, Cahabon (Champion); Nicaracua, Chontales (Janson). 
Upper surface of a brilliant brassy colour; the head indistinctly punctate, the thorax 
almost impunctate, the elytra very sparingly and somewhat obsoletely punctate and with 
