BATRISUS. ll 
sex. The larger number of the Tropical-American forms belong to the subgenus 
Arthmius; this subgenus has not been correctly treated up till now: the females of the 
species belonging to it are different in shape and usually in colour from the males, and 
have been regarded as specifically distinct ; the “table” recently given by Reitter of the 
South- and Central-American species known to him (Verh. Ver. Briinn, 1883, pp. 377 
and 378) requires emendation on this account, the insects enumerated by this author 
under Section B of Arthmius being females. 
§ 1. Thorax without any longitudinal channel, but with a transverse sulcus in front of 
the base; elytra without discoidal stria ; form different in the sexes. (Subgen. 
Arthmius.) 
1. Batrisus geniculatus. 
Rufo-testaceus, nitidus ; antennis pedibusque testaceis, illis parum elongatis ; capite plano, levigato, utrinque 
foveolato. 
Long. 2 millim. 
Mas antennis medio curvatis ; tibiis anterioribus ultra medium valde dilatatis, apice abrupte angustato. 
Hab. Mexico, Jalapa (Hage). 
The head is short and small; without sculpture, but with a distinct fovea on each 
side behind; the eyes small. The thorax is quite small, slender ; and without channels, 
except the delicate transverse sulcus in front of the base. 
The sexual differences are very considerable: the male is of a pallid rufescent colour 
and has longer elytra than the female, the female being of a more castaneous tint; the 
fifth joint of the antenne is considerably enlarged behind and with the two following 
joints forms a curve, the tenth joint is scarcely transverse; the front tibiz are greatly | 
dilated, and then below the middle suddenly narrowed ; the middle tibize are furnished 
with a minute internal uncus at the extremity; the apical half of the hind body is 
occupied beneath by a depression, and at the base of the latter is an elevated short 
carina from which a pubescent wing diverges on either side. Five examples were 
obtained by Herr Hoge, and I believe I have identified the sexes with certainty. 
2. Batrisus curvicornis. 
Batrisus curvicornis, Schauf. Nungq. Otios. ii. p. 2861; Reitt. Verh. z.-b. Ges. Wien, 1882, p. 378. 
Hab. Mexico (Bilimek ?, in coll. Reitter), Yucatan 1, Cordova (Sallé). 
Schaufuss’s description is a very poor one, and contains no characters that would 
enable his species to be discriminated from those allied to it, and I give therefore the 
male characters drawn from a Mexican example communicated by Herr Reitter. The 
unique exponent from Sallé’s collection which I take to be this species is in bad pre- 
servation. In the male the front tibie are slightly swollen from the base to below the 
middle, the apical third being again slender (this apical constriction is, however, not 
abrupt, so that the prominent angle terminating the swelling is very obtuse and not at 
C* 2 
