DENDROBIAS.—TRACHYDERES. 89 
The species taken by Mr. Belt, in the female sex only, is certainly distinct from 
D. mandibularis. It is narrower and more convex, as Dupont describes it; and the 
third joint of the antenne is shorter. In colour it resembles the pale variety figured 
by Dupont, but shows no darker markings at the base of the elytra. 
TRACHYDERES. 
Trachyderes, Dalman in Schénherr, Syn. Insect. 1. iii. p. 864; Lacordaire, Gen. Col. ix. p. 201. 
About fifty species of this highly characteristic American genus have been described. 
Its range extends from the basin of the La Plata to Mexico; but it has not yet been 
recorded from the United States or from Chili. Judging from the diversity of the 
specific forms, South Brazil appears to be the centre of distribution of the genus, 
the species being few and little varied in Central America and Mexico. 
1. Trachyderes succinctus. 
Cerambyx succinctus, Linneus, Mus. Lud. Ulr. p. 72. 
Trachyderes succinctus, Bates, Trans. Ent. Soc. 1870, p. 430. 
Trachyderes cayennensis, Dupont, Mag. Zool. 1836, Monogr. des Trachyd. p. 34, t. 156. f. 1. 
Hab. Panama.—Sovutu AMERICA, Venezuela, Guiana, Amazons region. 
2. Trachyderes subpilosus. 
Trachyderes elegans, var., Bates, Trans. Ent. Soc. 1872, p. 195°. 
T’. succincto similis, maris thorace minore elytrisque postice minus angustatis, scutello basi angustiore; corpore 
subtus (pracipue pectore) piloso, tibiis posticis apice nigris. Elongato-oblongus, castaneus nitidus, elytris 
medio fascia albo-testacea; antennis articulis 4°-11™ dimidio basali fulvis, interdum articulis 4° et 7° 
immaculatis ; corpore subtus variabili ; pedibus fulvis, femoribus et tibiis apice castaneo-fuscis. 
Long. 7-lllin. ¢ 9. 
Hab. Hoypvras, Rio Hondo (Blancaneaux) ; Nicaragua, Chontales (Belé*, Janson) ; 
Costa Rica, Irazu (Rogers). 
This species or local form is more nearly allied to 7. elegans than to any other of 
the species or subspecies belonging to the succinctus group of this difficult genus. 
But almost the sole structural character which distinguishes both from the South- 
American type species is the narrower scutellum, which is only noticeable when the 
specimens are very attentively compared. ‘The long brown erect hairs with which the 
under surface of the body, especially the breast, is clothed is certainly a good character, 
but is only visible in well-preserved specimens. The general form of the body is 
somewhat different in average individuals, especially of the male; but there are some 
in which this difference is not at all perceptible. I have never seen, however, in the 
best-developed males of 7. subpilosus and elegans the robust form which corresponding 
individuals of J. succinctus assume, with their voluminous thorax, thick and rough 
basal joints of the antenne, and tapering elytra. The colour of the hind tibize is 
subject to rare exceptions: in the majority the apex is dark brown, whilst in the true 
BIOL. CENT.-AMER., Coleopt., Vol. V., August 1880. n 
