92 Mr. J. O. Westwood's Description 



simplicibus, 5-articulatis, articulo 5to paullo longiori et gra- 

 ciliori : unguibus simplicibus. Mesosternumhrev'\^?\m\.\Ya, me- 

 tasternum transversum, coxis posticis parvis subrotnndatis. 

 Abdomen, ut videtur, 3-aiticulatum, segmento Imo maxirao, 

 2ndo brevissimOj 3tio mediocri subtriangulari. 



Species unica. Gnostus formicicola,\Nestw. (PI. VIII. fig. 1.) 



G. omnino rufo-castaneus, nitidus, corpore et pronoto glabris ; 



elytris punctato-striatis, corpore infra polite impunctato con- 



vexo. 

 Long corp. lin. I,= f2 ""'^• 

 Habitat in Brasilia, apud Santarem, in nidis Myrm'icce {Cremato- 



gastris^ victimce, Smith. D, Bates. In Mus. Britann., &c. 



Mr. Bates, supposing the insect (from its antennae) to belong to 

 the Paussidce, thus mentions the capture of this parasite, 



" No 140. Myrmicce {Cremalogasler^, neuter and fem., with its 

 formicarium formed in hollow, dried suspended sipos. Only one 

 female in each formicarium. This ant has a small species of 

 Paussidce almost invariably in its company, one, or at most two, 

 in each colony. No Paussus was found in any part of the sipo not 

 inhabited by the Myrmica." 



In our present dearth of knowledge upon the point we can only 

 speculate upon the object of the residence of this and numerous 

 other small Coleoptera in the nests of ants. That it is not without 

 the concurrence of the latter seems evident, not only from the 

 facility with which a colony of ants would dislodge the intruders, 

 but also from the fact that the ants have actually been seen carry- 

 ing some of these species of beetles — as, for instance, a species of 

 Paussus — in their jaws. Whether, like the Aphides, these beetles 

 emit peculiar secretions, to which the ants are partial, I am un- 

 able to state ; but certainly many of the ant-nest beetles are pro- 

 vided with small bundles of curved rigid setae on various parts of 

 their bodies, of which the uses are unknown, such as the tufts on 

 the heads of the Claviger, and on the pronotum of the Paussidce, 

 and in the Gnostus, on the under side of the middle of the third 

 joint of the antennae. Whether, also, on the other hand, these 

 beetles feed either on the eggs, larvae or pupae of the ants, or 

 upon their stores of food, is also conjectural. 



Mr. Bates, it will be seen, considers the insect above described 

 to belong to the Paussidce ; but, except in the paucity of joints in 

 the antennae, the constricted prothorax, and the short legs with 

 five-jointed tarsi, no actual relation can be traced with that family ; 



