Spiders and Their Near Relatives 



lothorax is distinctly longer than broad. It occurs in the 

 Atlantic States. 



Ideobisium tbeveneti (I. thev-e-ne'ti).— - This is a common 

 species in the States on the Pacific Coast. It differs from the 

 preceding in that the cephalothorax is about as broad as long. 



Genus IDEORONCUS (Id-e-o-ron'cus) 



The species of this genus differ from those of the preceding 

 in the possession of only a single pair of eyes. 



Ideoroncus obscunts (I. ob-scu'rus).— - This, our only species 

 of the genus, is common in the Far West. It is a comparatively 

 large species, the adult female often measuring one sixth inch 

 in length. 



Family OBISIID^E (O-bi-si'i-dae) 



The members of this family are most easily recognized by the 

 form of the spinneret of the chelicera, which is merely a small 

 knob (Fig. 44); the serrula is attached only at the base; the caia- 

 pace is not divided by a transverse suture; the abdominal scutae 

 art entire; and the femur and tibia of the first two pairs of legs 

 are rather long and slender. 



Four genera are represented in the United States; these can 

 be separated as follows: 



A. Tibia of the pedipalp normal; chelicerae of medium size. 

 (Subfamily Obisiinae.) 

 B. With four eyes, except in cave forms; palpi short and 

 stout. P. 51. Obisium 



BB. With no eyes; palpi very long and slender. P. 52. 



Blothrus 

 AA. Tibia of pedipalp very short and cup-like; chelicera? very 

 large. (Subfamily Chthoniinae.) 

 B. With four eyes, except in cave forms; palpi long. P. 52. 



Chthonius 

 BB. With only two eyes; palpi shorter. 1'. 5}. Lechytia 



Genus OBISIUM (O-bis'i-um) 



Five species of this genus have been found in the United 

 States; they are separated as follows: 



5> 



