DIOPENUS. 445 
DIOPGENUS. 
Last joint of the maxillary palpi broadly triangular, its apical and outer sides about equal; last joint of the 
labial palpi broad ovate, broadly truncate at the apex; mandibles at the apex narrow and very feebly 
bifid; head very short and broad, deeply and obliquely inserted beneath the anterior edge of the 
prothorax, and invisible from above; eyes very large and transverse, convex, very narrowly separated ; 
antenne stout, much compressed, short, reaching a little beyond the base of the prothorax, the joints 
closely articulated, broad at their base, and each widening a little outwardly—1 short and stout, 2 small, 
strongly transverse, 3 subtriangular, twice as long as 2, 4—8 gradually increasing in length and breadth, 
4 a little longer and broader than 3, 9 and 10 each the length of but narrower than 8, 11 longer and 
much narrower than 10 and very obliquely truncate at the apex; prothorax very large and broad, more 
than twice as broad as long, greatly expanded at the sides and broader than the elytra at the base, the 
base bisinuate and with a distinct median lobe, the hind angles very prominent, the sides very rapidly 
converging from the base; scutellum large, transversely scutiform; elytra short, narrowing from the 
base, very strongly margined ; epipleure-very broad and concave at the base, rapidly narrowing behind ; 
the flanks of the prothorax broadly and deeply concave; anterior coxe globose; prosternum very 
narrow, convex and abruptly declivous behind, and gradually sloping in front; intermediate coxe 
narrowly separated; legs very short and stout, broadly compressed; tarsi short, the basal joint very 
stout and that of the posterior pair shorter than the following joints united, the third and fourth 
joints of the anterior and intermediate pairs and the penultimate joint of the hind pair feebly lobed 
beneath ; claws pectinate; body broad ovate, rather depressed, pubescent, winged. 
This genus contains a single species of very peculiar aspect, which in its general 
facies departs widely from any known form of Cistelide and somewhat resembles 
Oochrotus. The chief characters lie in the short and broadly compressed legs and 
antenne, and in the head being very deeply sunk into the underside of the thorax, so 
as to be completely invisible from above. In the very large and greatly dilated thorax, 
with the hind angles projecting laterally beyond the base of the elytra, it approaches the 
preceding genus. The broadly concave flanks of the thorax and epipleure form 
cavities for the reception of the two anterior pairs of legs; the head in repose is 
obliquely withdrawn up to the eyes and does not lie upon the anterior face of the 
prosternum. 
The description is made from a single male example, which was captured by Herr 
Hoge during his second Mexican expedition. 
1. Diopenus compressicornis. (Tab. XX. fig. 16, 3.) 
Broad ovate, depressed, brownish-castaneous, slightly shining, thickly clothed with short pubescence. Head 
very finely and sparsely punctured; prothorax convex but depressed on the disc, closely and very 
eyes (3) very large, narrowly separated; antenne (¢) stout, rather short, ferruginous; prothorax very 
broad, the disc obsoletely canaliculate behind, the surface closely (but not densely), finely, and shallowly 
punctured; elytra finely punctate-striate, the interstices quite flat and finely and rather closely punc- 
tured; legs ferruginous; the lateral lobes of the last ventral segment broad and spoon-shaped and clothed 
with long hairs at the apex. 
Length 73 millim.; breadth 33 millim. (¢.) 
Hab. Nortu America, Texas. 
A single male example, kindly communicated by Dr. Horn. Much broader than M. crassicornis, the antenne 
simple in the male, the thorax more finely and more sparsely punctured, &c. 
