90 Mr. J. O. Westwood's Description 



XIV. Description of a new Genus of Coleopterous Insects 

 inhabiting the Interior of Ants Nests, in Brazil. By 

 J. O. Westwood, F. L. S., &c. 



[Read 7lU August, 1854.] 



The recent discovery of numerous remarkable species of Coleop- 

 terous insects in the interior of ants' nests, amongst the former 

 of which are to be included many species of the family Paussulce, 

 and the not less singular discovery of several most anomalous 

 species of Staphylinidce in the nests of white ants, in Brazil, have 

 induced our indefatigable correspondent in Brazil, Mr. W. H. 

 Bates, to search the nests of these different insects, in the hopes 

 of meeting with new species of Paussidce, or other equally curious 

 insects in such situations; nor has his search been entirely fruitless, 

 since, although he has not detected any member of the family 

 PaussidcjB (one of which had, liowever, been found on the Corcavado 

 mountain, near Rio Janeiro, by Mr. Miers), he has been fortunate 

 enough to capture several specimens of a small Coleopterous in- 

 sect, of an entirely new type, whose situation in the order is very 

 uncertain, and whose structure is, in many respects, as remarkable 

 as that of any known insect of the Coleopterous order. 



Having been allowed to examine these interesting insects in 

 detail, I am enabled to lay before the Society figures and descrip- 

 tions of all those important organs, upon the variations of which 

 the distribution of the order Coleoptera has been established ; 

 especially the structure of the antennae, trophi, tarsi, veining of 

 the wings, and the number of the segments of the abdomen. 



It is especially worthy of notice, that, whilst many of the species 

 of beetles found in ants' nests are destitute of organs of sight, the 

 eyes exist in the insect under consideration, of the ordinary size 

 and structure. 



The following are the characters of the genus which I propose 

 for the reception of the insect in question. 



Gnostus, Westw. 



Corpus minutum convexum, rigidum, politum, capite parvo, ely- 

 tris magnis oblongis, postice rotundatis, abdomen omnino 

 tegentibus. Caput minutum, in cavitate antica prothoracis 

 fere ad oculos immersum, antice rotundato-subporrectum, 

 pone oculos utrinque profunde et oblique impressum. Oculi 



