NORTH AMERICAN APTERA. 287 



TRA€KYRIII»JCJS Weed, 1892. 

 Body very hard ; dorsum a large plate, with a rough, coarsely 

 punctate surface. Front margin of cephalothorax furnished with 

 two denticulate tubercles. Eye-eminence prominent, with two rows 

 of large tubercles having spinose tips. Legs rather long, thickly 

 beset with spinose tubercles. Pores on margin of cephalothorax 

 rather small, oval ; palpal claw smooth ; inner distal angle of femur 

 very slightly and of patella quite strongly developed. First joint 

 of mandible furnished with a tooth on lower surface. Second legs 

 decidedly longer than fourth. 



Tracliyrhiiiiis favosus (Wood) Weed. 



Phalangium favosum Wood, Comm. Essex Institute, vol. vi, pp. 28-29. 

 Astrobunus (?) favosum (Wood). Weed, Amer. Nat. vol. xxiv, p. 917. 

 Trachyrhinris favosus (Wood). Weed, Amer. Nat. vol. xxvi, p. 529; Trans. 

 Am. Ent. Soc. xix, 193, pi. 10. 

 3IaJe. — Body 7 mm. long; 5 mm. wide. Legs: first, 21 mm.; second, 40 mm. 

 third, 21 mm. ; fourth, 26 mm. Body and members black, more or less mottled 

 with gray; body very hard, dorsum nearly square and quite level, having pro- 

 jecting angles on the anterior lateral corners; grayish, spotted with black, and 

 a faint central marking; coarsely punctate "so as to have a worm-eaten, almost 

 honey-combed appearance." Eye-eminence slender, rather high, light brown, 

 with several robust acute spines, which are at their bases gray, but are tipped 

 with black. Palpi roughened with numerous small blackish spines and spinose 

 hairs; inner distal angle prolonged in a pointed, conical protuberance. Legs 

 stout, thickly beset with spines. 



Female. — Body 7 mm. long; 4.5 mm. wide; palpi 4 mm. long. Legs: i, 18 

 mm. ; ii, 32 mm. ; iii, 17 mm. ; iv, 25 mm. Similar to male. 



A very peculiar and rather common species. Brookings. 



Subfamily PnALANGiiNiE. 



Teguments soft or subcoriaceous, not greatly roughened. Segments 

 indicated by strise, which are often obsolete. Five ventral segments ; 

 a single anal piece ; two lateral pores easily seen ; maxillary lobe 

 of palpus with two tubercles. 



The tw^o genera occurring in South Dakota are distinguishable 

 by the character mentioned below. 



A tooth on ventral surface of first joint of mandibles L<iobiiiium. 



No tooth on ventral surface of first joint of mandible I'lialaiigitiui. 



L.IOBITNUM C. Koch, 1839. 

 This genus is defined by Simon practically as follows : Teguments 

 soft or subcoriaceous. Striae of the cephalothorax and of the three 

 last abdominal segments very distinct ; those of the anterior seg- 



TEANS. AM. ENT. SOC. XX. OCTOBER, 1893. 



