The Pselaphid^ of North America. 45 



shallower, with its discal lines short; the other three foveae 

 are sharp and deep, the discal lines of the two middle ones 

 nearly equal in length, reaching beyond the middle; sutural 

 line deep, slightly arcuate, humeral tubercles strong, but not 

 prominent. Abdomen narrower than the elytra, border broad, 

 arcuately convergent; first segment one-fourth as long as 

 wide, depressed at the base in the middle third; the fourth 

 segment (6) similar at the base to the first, with two lunate 

 depressions, which meet in the middle, Mesosternum (5) 

 deeply impressed, anterior cox^ conical, contiguous, with a 

 minute sharp tubercle on the exterior tip. Head punctured 

 beneath, with a fine carina in the middle. 

 Habitat. California. (Alameda County.) 



O. coNVEXus, Casey. Form the same as in striatiis. Length 

 1.9 mm. 



Eyes their own length from the base. Antennce with the 

 first and second joints cyHndrical, last joint as long as the five 

 preceding ones. Prothorax as wide as long, base two-thirds 

 of the width, longitudinal sulcus very slightly dilated near the 

 middle. Elytra with the two middle fines equal, two-thirds 

 of the elytral length. 



Habitat. California. (Sonoma County.) 



O. ABBREViATUs, Casey^ differs from convexus by the base 

 of the prothorax being three-fourths of the pronotal width, the 

 longitudinal sulcus fine, not dilated. Elytra with the middle 

 lines unequal in length; the inner four-sevenths, the other three- 

 sevenths of the elytral length. Length 1.9 mm. 



The difference between these two is very slight. In O. 

 striates the length of the elytral lines vary, and the pronotal 

 longitudinal sulcus does not always end so abruptly anteriorly. 

 Repeated examination of many specimens prove to us beyond 

 doubt the identity of O. striatus^ convexus and abbreviatus. 



O. MONTANUs, Casey. Form more slender, depressed. 

 Length 1.8 mm. 



The basal joints of the antennse are smaller than in the other 



