I'oMdNV (lH.I.KCJK .!olHNM. OK KxTIIMllI.nli V 631 



OBISIUM 

 Tlu' species of tliis peiiiis are ratliir uiieoininoii : seieriil ociMir under stone*. 

 so that more tlioroujjli collectinjj will prc)l)al)ly discover more tlinn the one species 

 now known from f'alifornia. 



Obisium macilentum Siiium 

 (Fiijtire '210. G) 

 Pale yellowish brown, legs jmler; hard parts shining; ccphalothorax one- 

 fourth longer than broad, sides jiarnllel : mandibles al)out one-half the length of 

 the cephalothorax ; pedi))al])i very long and slender, with long. fine, scattereii 

 hairs; femur as long as the cephalothorax. fingers longer than hand. 

 From Mariposa, Clariiiiont and Mt. .*shasta. 



IDEORONCUS 



The single species of this genus is very common in the Northwest, among 

 fallen leax<s and in moss. 



Ideoroncus obscurus lllo. 



.Abdomen elong.ate, slender: eeph.alothorax a little longer th.in broad, slightly 

 narrowed and rounded in front, with few scattered hairs; pcdipalpi rather short, 

 femur hardly as long ;is cephalothorax. fingers shorter than hand, which is about 

 twice as long as broad, all with fine, short, simple hairs. 



From Lake Tahoe. 



IDEOBISIUM 

 One of the two species (I. Ihreveneii) is the most common Pscudoscorpion on 

 the Pacific Coast ; the other species is known from only one specimen. 

 1. Cephalothorax broadest at eyes; fingers more curved; very large 



species; dark, red-brown. magnum 



Cephalothorax broadest behind: fingers nearly straight, of moderate 



size, more yellowish brown. Ilirrvnirli 



Ideobisium magnum lianks 



Cephalothorax and palj)! dark red-brown, scuta- brown, legs pale. \ rounded 

 tubercle in middle of front margin of cephalothorax; eyes less than one-half their 

 diameter apart; stylet slender, with an outer bifid branch toward tip; pedipalpi 

 much as in /. threreneli, with fine hairs, those on fingers quite short and dense. 

 Length 6.5 mm. 



From Mt. Shasta. 



Ideobisium threveneti Simon 

 (Figure 210. A) 

 Pale reddish brown to yellow-brown: cephalothorax nearly square, but 

 broader behind, and the front slightly rounded; eyes almost touching each other; 



