OCTHEBIUS. 91 
and behind the middle the sides are abruptly narrowed, so that a prominent minute 
acutely rectangular angle is formed some distance in front of the base; there is, 
however, a white pellucid membrane bordering all the side of the thorax, and even 
extending round the front, so as to fill up all the inequalities and project beyond 
them. The legs are rather short and stout; the anterior and middle tibive are rather 
broad and somewhat flattened, the middle tarsi quite thick. 
Mr. Champion has sent three specimens of this minute but remarkable insect. It 
has some points of resemblance with the European subgenus Henicocerus, and it is 
probable, from its strong middle legs, that it adheres to rocks in rapid waters, as do 
the Henicocere. 
2. Octhebius parvulus. 
Parvus, depressus, fuscus, capite thoraceque nigro-eneis, nitidis ; antennis, palpis pedibusque sordide testaceis ; 
vertice biimpresso; prothorace impunctato, canaliculato, sexfoveolato, marginibus valde irregularibus, 
membrana magna pellucida auctis ; elytris haud striatis, sat fortiter seriatim punctatis, sat nitidis. 
Long. #, lat. 3 lin. 
Hab. Mexico, Guanajuato (Dugeés, coll. Sallé). 
Head without punctuation, with the clypeal suture very distinct, and two large 
definite impressions on the vertex. Prothorax strongly transverse, very irregular in 
outline, the front margin sinuate on each side behind the eye, and the side emarginate 
near the front, so that the front angle has the appearance of a lobe ; again, behind the 
middle the side is deeply notched, so that the outline is very irregular, but a delicate 
very transparent membrane extends all along the side and fills up the irregularities, 
and is even continued all across the front margin; the surface is quite without 
punctuation and is shining, the middle is deeply channelled, there is a deep oblique 
impression on each side near the middle, and in front of this two other deep impressions. 
The elytra have rows of definite moderately coarse punctures; the interstices are 
impunctate and destitute of pubescence. The under surface is nearly black. 
The Sallé collection contained three individuals of this species, under the name 
“QO. parvulus, EK. Dugés.” 
3. Octhebius apicalis. 
Brevis, convexus, supra seneus; prothorace elytrorumque apice plus minusve rufescentibus; aatennarum basi 
pedibusque testaceis, palpis fusco-testaceis ; prothorace omnium fortissime dense punctato, medio canali- 
culato, disco utrinque oblique unifoveolato, lateribus ad angulos posteriores excisis, excisione membrana 
parvula completa; elytris profunde striatis, striis fortiter punctatis, interstitiis angustis, leviter inequa- 
libus ; corpore subtus rufo-obscuro. 
Long. ?, lat. 3 lin. 
Hab. Guaremata, Guatemala city (Champion). 
This species is similar to the European 0. rufo-marginatus; its coarse sculpture 
allows it to be readily distinguished from the other Central-American species yet 
NN2 
