82 HYDROPHILIDA. 
the punctures, too, not being all of one size ; the punctuation of the scutellum is much 
obliterated. ‘The internal stric of the wing-cases are quite fine, while the external are 
a good deal deeper ; the interstices are quite sparingly and rather finely punctate. The 
legs are entirely yellow, even the front cox being clear yellow, and the middle and 
hind coxe having a decidedly yellow appearance. 
The male has the basal joints of the front tarsi greatly incrassate ; the fifth ventral 
segment has a broad short emargination at the extremity ; the middle part of the base 
of this emagination forms an extremely short broad projection, the hind margin of 
which is slightly emarginate. In the female the base of the emargination is bidentate. 
The Californian B. styliferus, Horn, is evidently nearly allied to this remarkable 
species. 
7. Berosus flavicornis. 
Flavescens, capite late metallescente, prothorace medio vittis duabus parvulis fusco-zneis ; elytris maculis 
fuscis parvulis ; pedibus, palpis antennisque testaceis, harum clava nullomodo infuscata; prothorace sat 
crebre equaliter punctato ; elytris striis externis quam interne multo profundioribus, apicibus muticis. 
Mas nitidus, prothorace tantum subtilissime alutaceo. 
Fem. subopaca, prothorace elytrisque alutaceis. 
Long. 3, lat. 13 lin. 
Hab. Mexico, Oaxaca (Sallé). 
Closely allied to B. infuscatus; but of more flavescent tinge, with the male elytra 
quite shining, the club of the antennz as clear yellow as the base, the legs only slightly 
obscurer in colour at the base of the femora, the strie of the elytra deeper and more 
coarsely punctate, and with the base of the notch of the fifth ventral segment of the 
male distinctly bidentate. The size of the individuals is perhaps rather smaller, 
and the prothorax is more transverse. From B. falcatus the species is readily distin- 
guished by the ordinary form of the mesosternal lamina. 
8. Berosus mexicanus. 
Ovalis, angustulus, capite metallescente crebre punctato; prothorace testaceo, medio vittis latis vix divisis 
nigro-metallicis, subtiliter sat crebre punctato; elytris testaceis fusco-maculatis, sat profunde striatis, 
striis internis subtilioribus, interstitiis crebre haud subtiliter punctatis ; scutello obsolete punctato; anten- 
narum basi, palpis pedibusque testaceis, femoribus basi obscuriore. 
Long. 24, lat. 1 lin. 
Hab. Mexico, Guanajuato (Duges, coll. Sallé). 
This species appears to be closely allied in its structure to B. infuscatus, but is 
very readily distinguished by the smaller size and the larger dark marks on the thorax. 
The male anterior tarsi have only a moderate dilatation of the basal joints; and in the 
female the surface is scarcely rendered dull by being extremely finely alutaceous. In 
each sex the transverse notch at the extremity of the fifth ventral segment has, in the 
middle of its base, two very distinct projecting teeth. The mesosternal lamina is large, 
and its front angle almost rectangular, showing scarcely any projection. The oblitera- 
