DIASTETHUS. 233 
the less densely squamose prosternum, with deeper glabrous sulcus, the plicate elytra, 
and the simply unguiculate anterior tibie in both sexes. The examples with cas- 
taneous elytra are probably immature. 
19. Diastethus impressipennis, sp. n. 
Very like D. bidentatus, but broader ; the prothorax a little less convex, with the sides arcuately converging 
from the base; the elytra less depressed along the suture, and with a shallower transverse depression on 
the disc beyond the middle ; the under surface more sparsely punctate, and with the scattered hair-like 
scales finer; the prosternal sulcus a little broader; the femora sharply bidentate and rather deeply 
sulcate beyond the middle. 
Length 6-7, breadth 4-41 millim. (.) 
Hab. Mexico (Mus. Brit.), Toxpam (Sallé), Cordova (Hége). 
Three females, differing from the same sex of D. bidentatus as noted above. In its 
general shape D. impressipennis agrees with D. mexicanus. From D. brevis and D. ater 
it may be known by the transverse depression on each elytron beyond the middle. 
20. Diastethus humerosus, sp. n. (Tab. XIII. fige. 16, 16a, 3.) 
Rhomboidal, convex, shining, black, the prothorax rufescent, the elytra each with a very large, transverse, 
testaceous, humeral patch which nearly reaches the suture; glabrous above and beneath. Rostrum 
strongly arcuate, long, very sparsely, finely punctate. Antennal club stout, acuminate-ovate, as long as 
joints 3-7 of the funiculus united. Prothorax convex, rapidly, arcuately narrowing from the base, 
strongly constricted in front, the base obliquely foveate on each side of the median lobe; smooth. 
Scutellum small, transverse. Elytra short, triangular, depressed along the suture, the humeri rounded 
and forming a continuous outline with the sides of the prothorax ; sharply striate throughout, the striz 
obsoletely punctate, the interstices smooth and feebly convex. Beneath coarsely punctate, the ventral 
segments 2-5 smoother, 1 broadly depressed in the middle and 5 closely ciliate along the apical margin ; 
prosternum with a broad, smooth, flattened space down the middle, which is bifoveate in the apical con- 
striction, the anterior cox widely separated. Legs sparsely punctate ; anterior femora feebly, the others 
distinctly dentate, the tooth on the posterior pair acute; tibize subangularly dilated on the outer edge 
near the base, the anterior pair sinuous; tarsal joints 2 and 3 broad. 
Length 22, breadth 13 millim. (d.) 
Hab. Panama, David (Champion). 
One male. Smaller than D. humeronotatus, the prothorax not so convex on the 
disc, the elytra sharply striate throughout, the humeri less swollen, the testaceous 
patch nearly reaching the suture, the rostrum less bowed at the base, the tibiz 
subangular at the base externally. 
21. Diastethus castaneus, sp. n. (Tab. XIII. figg. 17,174, 3.) 
Subrhomboidal, short, castaneous or ferruginous, glabrous above. Rostrum (¢) strongly arcuate, long, the 
basal portion thickened and coarsely punctate, the apical portion sulcate at the sides and somewhat 
closely punctate, () longer and with the apical portion very much smoother, the antenne inserted far 
behind the middle, the club oblong-ovate, stout. Prothorax rounded at the sides anteriorly, strongly 
constricted in front, gibbous at the middle and obliquely depressed or sulcate on each side of this, the 
surface finely punctate or smooth. Scutellum transverse. Llytra short, triangular, the disc slightly 
swollen below the base and transversely depressed at the middle, the suture also depressed anteriorly, the 
BIOL. CENTR.-AMER., Coleopt., Vol. IV. Pt. 5, Movember 1907. 2HH 
