PoMoxA f'()i.i.K(;i': .JoriiNM. ok F.xtomoi.ogv 639 



OBISIUM 



The specif's of this jjenus art' r.itlicr iincoininon ; several occur under stones, 

 so tliat iiiort' tliorough coUccting will ])robab]y discover more than the one species 

 now known from California. 



Obisium macilentum Simon 

 (Figure 210, G) 

 Pale yellowisli brown, legs paler; iiard parts shining; cephalothorax one- 

 fourth longer than broad, sides parallel; mandibles .-ilionl one-half the length of 

 the cephalothorax; pedipaljii very long and slender, with long, tine, scattered 

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

 From Mariposa, (larcmiint and Mt. Shasta. 



IDEORONCUS 



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

 fallen leaves and in moss. 



Ideoroncus obscurus Bks. 



Abdomen elongate, slender; cephalothorax a little longer than broad, slightly 

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

 femur hardlj' as long as 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. threvcneti) is the most common Pseudoscorpion 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. threveneti 



Ideobisium magnum Ranks 



Cephalothorax and palpi dark red-brown, seutae brown, legs pale. A rounded 

 tubercle in middle of front margin of ce])lialothorax ; eyes less than one-half their 

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

 much as in I. threveneti, 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; 



