2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. lu 



time of this wi^iting, certain of the differences distinguishing Thalkethops 

 grallatrix, new genus, new species, from the Kethops species seem at 

 least qualitatively to justify my action. 



Thalkethops and Kethops stand alone within the scolopocryptopine 

 constellation in their possession of cryptopiform ultimate legs (see 

 note 1, p. 13) and lack of sclerotized plates or other appurtenances 

 on the anterior prosternal margin (fig. 13). The lack of prehensorial 

 spinous processes of the basal article distinguishes both genera from 

 the two closely allied genera, Scolopocryptops and Dinocryptops (see 

 note 2, p. 13). They also differ from Kartops in lacking prosternal 

 armature. Newportia and Tidops are readily signalized by their 

 seventh pedal segment spiracles, which Thalkethops and Kethops lack. 



I believe the most strildng superficial features of Thalkethops are 

 also prominent among the features giving it its generic identity, 

 namely, the extraordinarily long antennal articles (fig. 5), and the 

 long, thin, almost stiltlike legs (hence grallatrix, a female stilt walker, 

 see fig. 14). Additional characters of significance are the following: 

 T. grallatrix: Tarsi 1-21 each with a nearly complete circumarticular 

 suture (fig. 3), hence each essentiall}' bipartite; sternital cross-sulci 

 and submarginal sulci absent. Kethops spp.: Tarsi 1-21 each undi- 

 vided, not suturate (fig. 12) ; sternital cross-sulci more or less and 

 submarginal sulci always distinct. Finally, the following characters 

 may prove to differ consistently between the two: T. grallatrix: Each 

 first maxillary coxosternum with a thin longitudinal and essentially 

 membranous strip (fig. 7); coxopleural ventral margin without a 

 submarginal sulcus, its edge not reflected to form a low flange. 

 Kethops spp. : Each first maxillary coxosternum without a thin mem- 

 branous strip (at least in T. euterpe Crabill) ; coxopleuron with a sub- 

 marginal sulcus, with a flangelike reflected edge (at least in T. euterpe 

 Crabill and T. utahensis (Chamberlin), the genotype). 



Several features of T. grallatrix suggest adaptation for cave life. The 

 long, light, thin legs seem well suited for swift passage along the 

 cluttered cave floor and over the walls and perhaps along the ceiling. 

 The pale, virtually transparent tergites and appendages may repre- 

 sent a loss of pigmentation such as is well known to occur commonly 

 in many kinds of cavernicoles. 



Thalkethops, new genus 



Generic diagnosis: Color: Tergites, sternites, and parts of legs 

 mostly translucent, the underying musculature plainly discernible 

 underneath. Antennae, each with 17 articles; each article extra- 

 ordinarily elongate. Cephalic plate without eyespots or margins; 

 posteromedially with a pair of short, slightly divergent sutures. 

 Maxillae : First, each coxosternum with a weak longitudinal membra- 



