THE LARGER GRAIN-BORER. 49 
Genus DINODERUS Stepli. 
Antennae inserted in front close to the eyes; the basal joint short, robust; 
the second subglobose; the five following minute, nodose, subcoarctate ; the re- 
mainder forming an elongate perfoliated club, of which the two basal joints 
are conic-trigonate, slightly produced within, and the terminal one subglobose, 
compressed. Palpi short, terminal joint minute, conic; mandibles exserted, 
acute ; head short, transverse, with the neck thick ; eyes globose ; thorax short, 
rounded, very gibbous, and rugose in front ; elytra retuse posteriorly ; body 
elongate, cylindric ; tibiae compressed, denticulated externally ; tarsi short, 
simple. 
For the further identification of this species Horn's original de- 
scription is quoted. 
Dinoderus truncatus Horn. 
Rufopiceous, moderately shining, surface sparsely clothed with very short 
hair. Front moderately, densely punctate. Thorax as wide as long, gradually 
arcuately narrowed from base to apex, margin very finely serrate, disc ante- 
riorly, roughly granulate, posteriorly, feebly but densely muricate. Elytra 
with coarse, deep, closely placed punctures, arranged in moderately regular 
striae, except near the scutellum, intervals not elevated, declivity abrupt, flat, 
densely punctate, acutely margined. Body beneath opaque, obsoletely punctate. 
* * * The marginal ridge of the declivity encloses an exact semicircle, 
while the face of the declivity is nearly vertical to the axis of the body. 
Length 3-4.3 mm., width 1.2-1.8 mm. 
With the related species Rhizopevtha dominica, which has been 
treated in the preceding paper, the present form, Dinoderus trun- 
catus, is not at all likely to be confused. The former is a much 
smaller insect, proportionately more slender and with a rough sur- 
face, whereas the species now being considered is comparatively 
smooth and somewhat shiny. It has several times been confounded 
with D. punctatus by entomologists. These last two species are 
alike in form, size, and color, the difference being in minute but 
distinct structural details. D. punctatus appears to confine itself 
to dead roots and stumps and has not attracted attention, so far as 
known, by its occurrence indoors. 
In some way truncatus was entirely overlooked by Gorham in 
his consideration of the Ptinidse (including Bostrychidse) in the 
Biologia Centrali-Americana, but pusillus (dominica), suhstriatus, 
and punctatus are included. In the United States National Museum 
are two specimens of truncatus labeled, respectively, " In rice, Guate- 
mala, March 11/84," and "Apate dubius E. Dug." The species is 
obviously common enough in Central America, and it is not impossi- 
ble that Gorham failed to separate truncatus from punctatus. 
The accompanying illustration (fig. 9) shows the characteristic 
structure of the beetle at a ; b represents the larva which, it will be 
noted, strongly resembles better known bostrychids, such as the red- 
