bartsch: northwest coast moi^lusks 



569 



than the diameter of the plug. Of these three — Micranelluni ped- 

 roense, catalinense, and profundicolum — have the anterior portion of 

 the adult shell bulbously expanded, while in the other two, M. barkley- 

 ense and oregonense, the diameter does not increase at the anterior ter- 

 mination. Of those with the bulbously expanded anterior portion, M. 

 pedroense has very fine closely spaced annulations, there being about 

 a hundred present in the adult segment of the shell, while in M. cata- 

 linense and profundicolum the annuli are less numerous and more pro- 

 nounced, there being about seventy-five in the last segment. The 

 shell of M. catalinense is shorter and stouter than that of M. profundi- 

 colum. The two species which lack the bulbous anterior expansion, 

 M. barkleyense and oregonense, are distinguished from each other at 

 once by their great difference in size, M. barkleyense being both longer 

 and thicker than Micranelluni oregonense. 



Two of the seven species, M. rosanum and crebricinctum, have the 

 spur of the plug expanded basally to cover the entire width of the 

 plug. Of these, M. rosanum is easily distinguished from M. crebri- 

 cinctum by being much longer and having the annuli much more distinct 

 than M. crebricinctum. 



TABLE 3 

 Additional Data Pertaining to the Above Micranellums 



Micranellimi pedroense, sp. 



nov 



Micranelliim catalinense, sp. 



nov 



Micranellum profundicolum, 



sp. nov 



Micranelluni barkleyense, sp 

 nov 



Micranellum oregonense, sp 

 nov 



Micranellum rosanimi,sp. nov. 



Micranellum crebricinctum 

 Carpenter 



