327 



Hand with a short stalk, considerably shorter than tibia, nearly twice 

 as broad, the outer side very little convex, the inner side very strongly 

 so , next to swelled. Fingers considerably longer than hand , slender 

 and strongly curved, the fixed finger with Ioav, angular teeth, the 

 moveable finger with some very low teeth in the distal part. 



Mandibles very robust (much alike those oi Mierocreagris gigas), 

 quite as broad as céphalothorax, strongly narrowing forwards, the 

 moveable finger longer than the trunk, sinuated on the outer side, with 

 a long, simple, curved galea, with no teeth. 



Legs : the femora minutely shagreened. The two anterior pairs of 

 legs are composed of coxa, trochanter, femur pars basalis, femur pars 

 tibialis and two tarsal joints, the distal tarsal joint longer than the pro- 

 ximal one; the two posterior pairs of legs are composed of coxa, trochan- 

 ter, very broad femur with rather indistinct trochantin division some- 

 what above the middle, tibia and two tarsal joints, the distal joint nearly 

 twice as long as the proximal one. The hairs of the legs pointed. Claws 

 simple. 



Length 4 mm, l)ut abdomen is much contracted, the width of ab- 

 domen 1,60 mm. 



Measurements: céphalothorax: long. 1,35; lat. 0,96. Mandibles: 

 long. 0,54. Temur: long. 1,44; lat. 0,32. Tibia: long. 1,36; lat. 0,40. 

 Hand: long. 1,12; lat. 0,70. Fingers: long. 1,52 mm. 



Chile: Santiago 1 specimen (Dr. Silvestri). 



Very much allied to Ideobismm [Ideoronciis] pallidnin Balzan, and 

 it is not (juite impossible, that Balz an' s specimens may have been young 

 ones of this species, but till this is decided, it is impossible to join them, 

 the difference being too great. The most important differences are: 

 jxdlidum is only 2 mm long, the palps are to be quite smooth, band 

 longer than tibia, fingers only a little longer than hand, céphalothorax 

 smooth. 



Genus: Chthonins, 



Subgenus: Pseudochthonius. 



Chtkonius Simoni Balzan. 



Uruguay: Salto 1 specimen. 



Subgenus: Chthonius s. s. 

 Chthonius Silvestrii nov. sp. 



Two small eyes on each side , the anterior eye about one diameter 

 from the front margin, the posterior one about the same distance from 

 the first; the anterior eye is distinctly developed, the posterior one is 

 less developed. 



Colour: palish, abdomen with some few very large, white spots. 



Céphalothorax as long as broad, only little narrowing backwards, 

 nearly squarish, the sides very slightly convex, front margin slightly 

 convex, the central part straight with some minute teeth; minutely 

 shagreened and somewhat glossy with some few long, pointed hairs. 



