BIDESSUS. 21 
lateribus parum distincte rugulosis, basi in medio profunde transversim depresso ; elytris dense fortiter 
punctatis, crista elongata elevata; corpore subtus punctis magnis, coxis grosse punctatis. 
Long. vix , lat. 3 lin. 
Hab. Guatemata, Paso Antonio, 400 feet (Champton). 
This species is no doubt very closely allied to the North-American Hydroporus 
exiguus; but, although I have no opportunity of comparing the two, I believe it will 
be found that the present insect is rather smaller, and rather more coarsely and less 
closely punctate on the elytra. 
5. Bidessus quadrisignatus. 
Ovalis, parum elongatus, convexus, nitidus, sine pubescentia, subtus piceus, supra nigricans, thorace trans- 
versim in medio, elytris maculis quatuor magnis, antennarum basi pedibusque testaceis; elytris crebre 
fortiter punctatis; clypeo in medio marginato. 
Long. 13, lat. 3 lin. 
Hab. Mexico, Guanajuato (Duges, coll. Sallé); Guatemata, San Geronimo (Champion). 
Head impunctate; thorax with distinct punctuation about the middle, especially 
towards the base, but almost impunctate at the sides, the plica rather deep and 
distinct. Elytra nearly black, with a large subhumeral and a rather smaller ante- 
apical spot yellow; very distinctly punctate, the punctuation rather coarse near the 
suture, fine at the sides; the immediate vicinity of the suture is impunctate; and this 
gives rise to some appearance of a sutural stria. The hind coxe bear some rather 
coarse punctures, as do also the wings of the metasternum; the middle of the meta- 
sternum has only some very fine punctures. The legs are reddish yellow. 
The tarsi in the two individuals before me are slender ; and I see no sexual differences. 
The species is readily distinguished from B. lynceus by the polished upper surface 
and less dense punctuation ; it has a general resemblance to the European Hydroporus 
goudoti and H. pumilus, Aubé. 
The specimen from Guanajuato is rather more closely and finely punctate and 
somewhat darker in colour than the San Gerénimo individuals. 
6. Bidessus quadrinotatus. 
Ovalis, convexus, sine pubescentia, nitidus, subtiliter punctatus, rufus, thorace ad marginem anticum et ad 
basin elytrisque nigricantibus, his signatura transversa subbasali, alteraque longitudinali ante apicali 
testaceis ; pectore abdomineque piceis; clypeo in medio marginato. 
Long. 1, lat. § lin. 
Hab. Mexico, Cordova (Sallé). 
Antenne elongate, red. Head large, obscure fuscous red, almost impunctate, the 
clypeus rather indistinctly margined in the middle in front. Thorax finely and mode- 
rately closely punctate, the punctuation more distinct on the middle than elsewhere ; 
the basal impression on each side deep and distinct. Elytra rather closely, but finely 
