v SCYDMAENIDAE GNOSTIDAE PSELAPHIDAE 223 



in South Australia and Tasmania. The most remarkable form 

 known is perhaps the Australian genus Ptomaphila (Fig. 104, B). 

 The classification of the family is due to Dr. Horn. 1 The 

 only change of importance that has since been suggested is 

 the removal of Sphaerites from this family to Synteliidae. 

 Anisotomidae and Clambidae have been considered distinct 

 families, but are now included in Silphidae. 



Fam. 16. Scydmaenidae. Minute Insects allied to Silphidae, 

 but with the hind coxae separated, and the facets of the eyes coarser ; 

 the tarsi are Jive-jointed ; the number of visible abdominal segments is 

 six. These small beetles are widely spread over the earth's surface, 

 and about 700 species are now known, of which we have about a 

 score in Britain ; many live in ants' nests, but probably usually 

 rather as intruders than as guests that have friendly relations 

 with their hosts. Nothing is known as to their life-histories, but 

 the food of the imago, so far as is known, consists of Acari. Afastigu* 

 is a very aberrant form, found in moss and dead leaves in Southern 

 Europe. By means of Brathinus the family is brought very near 

 to Silphidae ; Casey, however, considers Brathinus to belong to 

 Staphylinidae rather than to Scydmaenidae. The South European 

 Leptomastax is remarkable on account of the slender, long, sickle- 

 shaped mandibles. The Oriental genus Clidicus is the largest and 

 most remarkable form of the family ; it has a very slender neck 

 to its broad head, and is more than a quarter of an inch long. 



Fam. 17. Gnostidae. Minute Insects with three-jointed 

 antennae, Jive-jointed tarsi, and three apparent ventral segments, the 

 first of which, however, is elongate, and consists of three united 

 plates. Elytra entirely covering the after-body. The family con- 

 sists of two species which have been found in the nests of ants, 

 of the genus Cremastogaster, in Brazil. 2 



Fam. 18. Pselaphidae. Very small Insects ; the elytra much 

 abbreviated, usually leaving as much as half the abdomen uncovered ; 

 the maxillary palpi usually greatly developed, and of a variety of 

 remarkable forms ; the segments of the abdomen not more than 

 seven in number, with little or no power of movement. Tarsi with 

 not more than three joints. These small Coleoptera mostly live in 

 the nests of ants, and present a great diversity of extraordinary 



1 Tr. Amer. ent. Soc. viii. 1880, pp. 219-321. 



2 AVestwood, Tr. ent. Soc. London (N.S.) iii. 1855, p. 90; Wasmann, Krit. 

 Verzeichniss Myrmekoph, Arthropod. 1894, p. 121. 



