STAPH YLINIDiE. 



73 



inflexed beneath the body, the inflexed portion being often separated 

 from, the upper surface by a distinct ridge ; prosternurn variable, 

 with the coxal cavities usually open behind ; tarsi 5- 4- or 3-jointed ; 

 wings tuithout cross-veins or enclosed areas. 



The chief character of the Staphylinidjs lies in their very 

 short elytra, from which they derive their old name of Brach- 

 elytra. But although these organs are so small, yet they conceal 

 large and ample wings, which are very beautifully packed and 

 folded away beneath them, and in spite of their apparent un- 

 wieldiness they can be almost instantaneously unfolded for flight. 

 The refolding appears to take a longer time, and on warm days 

 species of Philonthus, Homalota, etc. may often be seen alighting 

 and running rapidly with 'their wings only folded laterally and 

 reaching to the apex of the abdomen ; but, as a rule, this is only 

 for a few moments. Dr. Sharp (7. c. p. 225) says that " it is 

 thought that the power of curling up the abdomen is connected 

 with the packing away of the wings after flight ; but this is not 

 the case, for though the insect sometimes experiences a difficulty 

 in folding the wings under the elytra after they have been 

 expanded, yet it overcomes the difficulty by slight movements of 

 the base of the abdomen, rather than by touching the wings 

 with the tip." The author has observed a species of Philonthus, 

 or an allied genus, when apparently in such difficulty, set 

 all right by a sudden curling up of the abdomen, the wings dis- 

 appearing smoothly under the elytra as if by magic ; so far as 

 could be seen, they were not touched by the tip of the abdomen 

 but were driven home by a sudden push from its base. 



The eyes in the StaphylhstiDjE are very variable, and rarely 

 they are altogether wanting ; sometimes they are very small, and 

 in other cases again (e. g., Stenus and Megalops) they are very 

 large and prominent, rendering the head the chief feature of the 

 body. Two frontal ocelli are present in medium and one in 

 Phloeobium. Some authors consider that the presence of ocelli 

 testifies to the great antiquity of a family ; thus Lameere says 

 (Ann. Soc. Ent. Belgique, 1900, p. 373) : — " La presence d'ocelles 

 chez Pteroloma de la famille des Silphides et chez les Omaliiens de 

 la famille des Staphylinides temoigne de la haute antiquite des 

 Staphyliniformes." Whether this is true can hardly be proved, 

 but it should probably be interpreted as the persistence of a 

 character which has been lost in most species. Every student of 

 Homoptera is familiar with the conspicuous frontal ocellus in 

 certain Cixiidjs. "When working at the Cixim^ of Central 

 America for the 6 Biologia Centrali-Americana,' I found this 

 ocellus varying much in size, even in the same species ; in some 

 species it was so small as to be hardly traceable, in others nothing 

 was left but the cicatrix, and in yet others there was merely a spot 

 marking the position it had perhaps once occupied in previous 

 generations. The retention of the ocelli by even a few species of 

 Coleoptera is, in any case, very interesting. 



