NAUTILUS. 125 



******* 



Succinea avara Say. 

 Succinea avara venncta Say. 

 Snrciiien avaru guadalitpensis Dull. 

 Sticcinea <irnr oreyonensis Lea. 



Succinea avaru rastlcann GUI. 



This completes the. list of the land shells of these islands so far as 

 I know them. 



The above arrangement of the Succineas may not meet the 

 approval of some conchologists, but these subfossils, as well as the 

 recent forms, go through those successive changes in the develop- 

 ment of the shell. 



\_Tu be concluded.^ 



A NEW SPECIES OF SUBEMARGINULA FROM CALIFORNIA. 



BY W. H. DALL. 



Subemarginula Yatesii n. sr>. 



Shell large, coarse, strong, whitish gray, or pale olive green on 

 the fresher portions, especially a very narrow margin about the base; 

 sculptured with strong, not dichotomous, radial ribs, of which about 

 20 are primary, between each two of which lie from one to foul- 

 secondary riblets, most numerous at the sides of the shell ; besides 

 these there is a very strong anal fascicle, higher and stronger ex- 

 ternally than any of the ribs, extending from the apex, and ending in 

 front at a notch about 3.5 mm. deep and rounded above and behind ; 

 the radiating sculpture is sharply and irregularly imbricated by the 

 rude and profuse incremental sculpture, which is too close and irre- 

 gular to form reticulation ; apex small, pointed, not much elevated, 

 situated three-fifths of the way from the front to the posterior margin ; 

 the fascicle descending from it swerves a little to the right of the 

 median line of the shell ; interior wliite, the extreme margin pale 

 olive green but almost linear; anal furrow deep, extending nearly to 

 the apex, where it is lost in a very pale olive deposit of shelly 

 matter; margins crenulated by the sculpture ; muscular impressions 

 strong, the two recurved scars unequal, the. right one larger. Lon. 

 of shell 51, hit. 36, alt. 13 mm. 



This shell was received from Dr. L. G. Yates, of Santa Barbara, 



