54 Mr. Westwood on the Genus Ctenostome. 
the penultimate joint of the anterior, as well as of one of the intermediate, 
and of one of the posterior, tarsi, as bilobed. This joint, however, in 
all the legs is simple in both sexes of Ct. ichneumoneum; and also, f 
imagine, in all theotherspecies, else Dejean would doubtless have noticed it. 
The elytra of the male are elongated and rounded at the tips, whilst 
those of the female are less elongated, and truncated so as nearly to form 
three slight teeth. This character therefore, in this species at least, is a 
sexual and not a specific one. 
The penultimate segment of the abdomen of the male is emarginated 
beneath; the last segment in the females is long and pointed at the tip, 
and there are two lateral lobes above, united apparently on their inner 
surface. 
With reference to the geographical distribution of insects, it may be: 
mentioned that the genus Ctenostoma appears to represent in South 
America (of which all the species are natives) the Asiatic genus Colliuris. 
I am happy in having come to the possession of the sexes of one of 
the species of this rare and interesting genus, and in being consequently 
enabled to illustrate it with the sexual characters given above, and to 
correct the specific characters of the same species given by Dejean. 
Ct. ichneumoneum. Dej., Species General, &c. v. 2. Suppl. p. 436. 2 
, Guerin, Iconogr. du Régne Animal, Insectes. pl. 3. 
fig. 3. 
Ct. nigro-subeneum, nitidum, elytris punctatis basi subtransversim rugosis, 
macula media transversa apiceque flavis. 
Long. Corp. g et 9, lin. 53. 
Habitat in Brasilia. In Mus. Dejean, nostr. g et 9. 
This is a very distinct species. The sexes are of equal size, and their 
general specific characters are precisely similar, except as before and 
after mentioned. The antenne are brownish black, with the first three 
joints yellowish brown, their upper surface being black. The surface of 
the head is nearly flat in front, and punctured, especially between and 
behind the eyes, and has upon its surface several rugosities forming two 
longitudinal channels between the eyes, and terminating behind them 
in a semicircular transverse ridge, behind which the head is narrower, 
smooth, and shining. The colour of the head, trophi and thorax is 
shining black, slightly bronzed ; the latter is highly polished and impune 
tate, and formed as in Ct. trinotatum, as described by Dejean; the elytra 
