120 HETEROMERA. 
TENEBRIO. 
Tenebrio, Linnzus, Syst. Nat. ed. x. p. 417 (1758) ; Lacord. Gen. Col. v. p. 379; Horn, Rev. 
Ten. N. A. p. 345; Motsch. Bull. de Moscou, xlv. pt. 2, pp. 26, 27; Lec. & Horn, Class. 
Col. N. A. p. 378 (1883). 
Neatus, Leconte, Class. Col. N. A. p. 233 (1862). 
This genus, as at present recognized, includes only the well-known cosmopolitan 
T. molitor and T. obscurus (both of which are now introduced almost all over the 
world through the medium of commerce) and their allies. 
1. Tenebrio molitor. 
Tenebrio molitor, Linn. Faun. Suec. p. 224 (1761) ; Sturm, Fn. ii. p. 219, t. 46. £. n-p ; Muls. Col. 
de France, Latig. p. 277; Horn, loc. cit. p. 345. 
Hab. Costa Rica (Van Patten).—Evrore ; Norra AMERICA, &c. 
Probably introduced from Europe. 
The following genera are of uncertain position. ‘Till the numerous undescribed 
species of tropical Tenebrionide are more fully worked out, it is better not to make new 
groups for these isolated aberrant forms, which, like Apolites, Catapiestus, and others, 
have at present few, if any, known allies. 
RHACIUS. 
Form of Calcar (Centorus, Muls.). Mentum variable, moderately large, subcordiform, flattened, and the 
anterior angles rounded (&. sulcatulus), or small, transverse, widest behind, and the angles rounded 
(R. quadricollis); ligula prominent, deeply emarginate in front; mandibles variable, pointed at the 
apex (2. sulcatulus), or slightly fissile (2. quadricollis) ; inner lobe of the maxille unarmed ; antennee 
short, stout, slightly widening outwardly, scarcely or about reaching the base of the thorax, third joint 
scarcely as long as the first and second united, fourth to sixth obconic and decreasing in length, seventh 
to tenth broader than long, eleventh large; head (as in Centorus) sunk into the thorax to the eyes, short, 
broad, narrowing from the eyes forwards ; epistoma more or less confounded with the front, truncate or 
feebly emarginate ; sides of the front not divergent, feebly swollen ; eyes broad, moderately large ; prothorax 
long, quadrate, scarcely narrowing behind, very distinctly margined at the sides, closely embracing the 
elytra; scutellum strongly transverse ; elytra long, narrow, scarcely wider than the thorax, widest at or 
near the base, narrowing gradually posteriorly, regularly and closely punctate-sulcate or punctate-striate, 
scutellar stria distinctly impressed, interstices flat or convex, very distinctly margined at the sides, 
humeri distinct ; epipleure narrow, narrowing gradually from the base and extending to the apex; 
prosternum flattened, produced, and truncate or rounded at the apex, not raised; middle coxal cavities 
open ; trochantin distinct; third and fourth ventral segments without distinct coriaceous hind margin ; 
legs short; intermediate and posterior femora (apparently in both sexes) swollen in the middle, and 
with a strong triangular tooth, between which and the apex emarginate; tibial spurs distinct; tarsi 
thinly clothed with spiny hairs beneath, last joint of the posterior pair about as long as the preceding 
joints united. Winged. Surface slightly pubescent or glabrous. 
The following characters, partly taken from unpublished MS. of Mr. F. Bates, have 
