276 [May, 



DESCRIPTIONS OF THREE NEW SPECIES OF CTENOSTOMA (TRIBE 



CICINDELIDES.) 



BY H. W. BATES, F.Z.S., Pres. Ent. Soc. 



The curious tiger-beebles forming the family Gtenostomidce 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 Cicindelce 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 Poneridce group. 

 In Lacordaire's classical work, the " Genera des Coleopteres," the 

 tropical American forms of the Ctenostomidcd were divided into three 

 genera, — ProcepJialus, Ctenostoma, and Myrmecilla, — 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 MyrmeciUa, a transverse lab rum, 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. obliquatum, Chaudoir) have the labrum and elytra of 

 Ctenostoma 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. corculum, des- 

 cribed below, which resembles Myrmecilla in labrum and labial palpi, 

 but has the elytra of Frocephalus. 



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 

 February, 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 here added will bring the number to 30. 



