44 
Mr. He W. Bates on 
^ . Antennse longitudine corporis^ articulis basalibus 
tribus aspere punctatis^ omnibus intus denticulatis ; 
tarsi omnes lati^ lobis rotundatis. 
$ . Antennae dimidium corporis attingentes, tenui- 
ter punctatae^ nec denticulatae ; tarsi lobis com- 
pressis. 
The thorax is coarsely scabrous on the sides in both 
sexes, and has a broad shining space in the middle, 
finely punctured ; the basal joint of the antennae is 
shorter and thicker than in any other known species. 
The female has not before been described. 
The species occurred at Santarem, Obydos and Manaos, 
on the Amazons. 
3. Ctenoscelis Nausithous. 
Buquet, Ann. Soc. Ent. Fr. 1843, p. 236, pi. 9, 
f. 2, c?. 
Ct. gracilior, thorace angustior; piceo-niger, thorace 
scabroso, spatio mediano laevi subtiliter punctato ; 
elytris apice rotundatis, angulis suturalibus dentatis. 
Long. 3 unc. 4 lin. 
^ . Antennae corpore longiores, articulis extus 
breviter tuberculatis, tribus basalibus subtiliter punc- 
tatis, reliquis laevibus. 
9 . Antennae dimidium corporis superantes, spar- 
sim punctatae ; tarsi la ti, lobis p os ticis acutis. 
The shape of this species is much more slender than 
in the rest of the genus ; the thorax of the female is 
scarcely to be distinguished from that of the same sex in 
Ct. Dyrrliaciis f but the elytra differ in being much nar- 
rower, and especially more parallel-sided ; the tibiae also 
are relatively longer, and more slender. 
I met with one example only of this species, a female, 
at Serpa, near the mouth of the River Madeira. E^ot 
being acquainted with the male, I have drawn up the above 
imperfect diagnosis from the description of M. Buquet, 
who obtained the insect from Bolivia. 
Lacordaire founds his generic characters of Ctenoscelis j 
in great measure, on the sexual differences in the punc- 
tuation of the thorax, as shown in Ct. ater and acantho- 
pus ; this part of his diagnosis will no longer be appli- 
cable, as Ct. Dyrrhacus and Nausithous show no such 
differences. 
