27G t'"*^' 
DESCRIPTIONS OF THREE NEW SPECIES OF CTENOSTOMA (TRIBE 
CICINDELIDES.) 
BY H. W. BATES, F.Z.S., Pees. Ent. Soc. 
The curious tiger-beetles forming the family GtenostomidcB have 
always been regarded with especial interest by coleopterists, on account 
of their rarity, and the singularity of their appearance ; these insects 
having a greater general resemblance to ants than to their near 
relatives, the GicindelcB proper. This resemblance is due to the globular 
form of the thorax, the constricted base of their elytra, and their dark 
bronzed colours ; and it is so great, that, when the insects are seen 
prowling in search of prey along the slender branches of trees, they 
can scarcely be distinguished from large ants of the PoneridcG group. 
In Lacordaire's classical work, the " Genera des Coleopteres," the 
tropical American forms of the Otenostomidce were divided into three 
genera, — Frocephalus, Ctenostoma, and iliyrmeciZZa,— distinguished from 
each other chiefly by the form of the elytra, which was parallelogram- 
mical in the first, dilated behind and gibbous in the second, and simply 
dilated behind in the third. To this character were added, in the case 
of the genus Myrmecilla, a transverse labrum, undilated 2nd joint of 
the maxillary palpi, and greatly elongated 3rd joint of the labial palpi ; 
but the new species which have been discovered since the date of this 
work have proved the inapplicability of these characters, for some 
species {e. g., G. ohliq^uatum, Chaudoir) have the labrum and elytra of 
Gtenostoma and the palpi of Myrmecilla ; and the three genera have 
been sunk into one (as long ago proposed by Erichson) in a revision 
of the group published by Baron Chaudoir, in the Bulletin dea 
Naturalistes de Moscou, vol. 33, 1860. As a further proof of the 
untenability of the three genera, may be instanced G. corcuhm, des- 
cribed below, which resembles Myrmecilla in labrum and labial palpi, 
but has the elytra of Procephalus. 
I took myself eleven species of Gtenostoma on the banks of the 
Amazons. As a hint to future travellers, I may mention that they are 
to be searched for at the close of the dry season, from November to 
Eebruary, and that the only way of finding them is to walk slowly 
along the pathways of second-growth forest, and examine carefully all 
the slender branches. When a specimen has been detected, the bushes 
may be beaten over an open umbrella, and thus made to yield all their 
contents, 
Twenty-seven well-defined species have been described by authors ; 
the three hero added will bring the number to 30. 
