90 _ HYDROPHILIDA. 
In Sallé’s collection there is an individual (which has lost its head) that may be a 
variety of this species, but it has the thoracic fovee deeper and longer; it is from 
Guanajuato, in Mexico. 
2. Hydrochus obscurus. 
Sat elongatus, supra metallescens; antennarum basi, palpis pedibusque testaceis, femoribus basi fuscis ; pro- 
thorace elytris angustiore, posterius sat angustato, ineequali ; elytris subparallelis, fere eequalibus, fortiter 
punctatis, striarum interstitiis angustis. 
Long. 13, lat. 3 lin. 
Hab. Guatemata, Paso Antonio, 400 feet (Champion). 
This species is very closely allied to A. debilis, but the elytra are more parallel, and 
the interstices of the elytra are even or nearly so, there being only indistinct traces 
of the elevations on certain portions of the interstices that exist in H. debilis. The 
five individuals before me show considerable variation in the sculpture of the prothorax 
in regard both to the foveole and punctuation, the former being sometimes conspicuous, 
sometimes indistinct, and the latter varying in closeness. 
OCTHEBIUS. 
Octhebius, Leach, Zool. Misc. 1. p. 90. 
This is a very distinct genus of about fifty described species of minute Hydrophilide. 
The registered species are principally natives of Europe. Seven species, however, have 
been described from North America, and there is no doubt the genus (many of the 
species of which inhabit salt and brackish waters) has a wide distribution. I am not 
yet, however, acquainted with any from South America. There is some difference of 
opinion as to whether the genus should be divided or not, Wollaston considering (Trans. 
Ent. Soc. Lond. 1871, p. 223) that Calobius is a valid distinct genus, and Bedel (Faune 
Col. Seine, i. p. 292) that Henicocerus of Stephens should be accepted. I have not at 
present thought it advisable to separate generically the remarkable 0. crassipes from 
the other species here described; but if the above genera be accepted, then O. crassipes 
will form another distinct genus ; it has the terminal joint of the palpi quite minute, 
but in some other respects departs widely from Henicocerus. 
1. Octhebius crassipes. (Tab. III. fig. 4.) 
Niger, supra levigatus, nitidissimus; antennarum basi pedibusque sordide testaceis; prothorace magno, medio 
profunde canaliculato, lateribus undique membrana pellucida auctis. 
Long. 4, lat. vix 3 lin. 
Hab. GuateMata, Duefias (Champion). 
This species is remarkable on account of its highly.polished impunctate surface. 
‘The outline of the prothorax is very irregular ; the front margin is sinuate on each side 
behind the eyes, then at the sides there is a small curved emargination near the front, 
