TAXONOMIC MORPHOLOGY 29 



these organs in our taxonomy. Certainly facet number is as good a character 

 as many others now in use. 



In Pselaphidae the eye varies from circular, through ovoidal to strongly 

 reniform and its shape, relative position, amount of ocular setosity are all 

 quite constant for a species population except where the sexes have differently 

 formed eyes. The loss or reduction of eyes is considered as a specialized con- 

 dition, and primitive stocks, therefore, are thought to have the eyes well 

 developed. Often loss or reduction is correlated with loss or reduction of func- 

 tional metathoracic wings, or both with habitat such as the deep mold or 

 cavernicolous species, occasionally with sex but no invariable rule may be 

 set forth in this respect. 



Nevertheless there has been considerable reduction or loss of compound 

 eyes in the Pselaphidae. Thus, in Euplectini, Mirus and Scotoplectus have no 

 eyes, Rhinoscepsis has reduced eyes in both sexes, and Autoplectios and 

 Eutyphlus have reduced eyes in the female sex. In Batrisini, Amaurops 

 (Troglamaurops) and Arianops have no eyes but replacing spines, Amaurops 

 {Amaurops) has neither eyes nor replacing spines, and Bergrothiella has re- 

 duced eyes. In Pselaphini, Pselaphiscnus has reduced eyes, and in Pselaphu^ 

 the eyes vaiy among the species from well-developed to greatly reduced. In 

 Goniacerini, Bibrax has the eyes represented each by a single facet. In 

 Aletopiini, Barrometopia has reduced eyes of ten facets each. In the Clavi- 

 gerinae, Adranes and Claviger have no eyes. 



Number of facets is much less well known, but offers great taxonomic pos- 

 sibilities. In Fustiger the species vary in number of ocular facets from 8 to 30 ; 

 in Hamotus the facet number varies among the species from 34 to 96. We are 

 at the threshold of our knowledge in this notable character. The new species 

 described in this paper have the facet number stated, but the implications 

 must await more examples. 



A novel feature is the facet structure of a new genus of termitophilous 

 tyrines, Tyrogatunus. Here the reniform eye of 62 facets has the dorsal third 

 of the eye composed of about 22 very flat, significantly wider facets, whereas 

 the ventral two-thirds has the more normal strongly convex type of facet. 



In the previous pages, certain salient structures have been discussed 

 comparatively. From this it is obvious that the pselaphids are most nearly 

 allied to Staphylinidae — in fact, they should be regarded as a specialized as- 

 semblage of an ancestral staphyliniform ancestor. The pselaphid tribe Faronini 

 is especially staphylinoid. As Casey noted (1893), the tarsus of Faronus is 

 quite similar to many Oxyteline staphylinids. Again, the first visible tergite of 

 Faronus has a transverse pubescent line which is found in some Omaline 

 staphylinids. The general resemblance of euplectines to Euasthetinae is also 

 suggestive. These euasthetine staphylinids have a distinctive pselaphoid habitus, 

 which goes beyond their small size and color, extending to the contour of the 



