44 THE NAUTILUS. 



Bivonia compacta Carpenter. Shore to 25 fathoms. Found 

 either singly or in contorted masses and not at all rare. 



Littorina planoxis Nuttall. Abundant. 



Littorina scutulata Gould. Abundant. 



Lacuna nnifvsciata Carpenter. Dead shells common and living 

 individuals not rare at low tide. 



Fossarus (Isapis) fenestratus Carpenter. Shore to 12 fathoms. 



Diala marmorea Carpenter. Shore to 12 fathoms. 



JZissoa acutilirata Carpenter. 12 to 25 fathoms; plentiful, but 

 usually dead. 



Rlssoina bakeri Bartsch. 12 to 25 fathoms ; rare. 



Rissoina pnrpurea Dall. 12 fathoms ; a single specimen. 



Barleia Italiotiphila Carpenter. Between tides ; plentiful. 



Calyptrcea mamillaris Broderip. 12 fatlioms ; no living specimens 

 found. 



Crepidula adunca Sowerby. Sliore to 20 fatlioms and everywhere 

 plentiful. Found almost invariably on shore attached to the shells 

 of the black turban, Chlorostoma funebrah. Specimens dredged 

 were usually of a lighter color, deeper, and distorted. 



Crepidula nivea Gould. Found at low tide, adhering to the under 

 surfaces of stones. 



Crepidula dorsata Broderip. Low tide to 20 fathoms, particularly 

 among sponges and kelp-roots. 



Crepidula lessonii Broderip. Low tide to 20 fathoms ; rather un- 

 common, but usually in old holes of Pholads, etc. 



Amalthea antiquata Linne. Found in large colonies attached to 

 the under surfaces of rocks at the Big Tide Pool. 



Lunatia lewisii Gould. Fishermen, etc. Not rare. 



Lunatia draconis Dall. Fishermen, etc. Also dredged alive in 

 12 fathoms of water. An examination of a number of individuals 

 of each of these species, as to whether the shells showed any very 

 noticeable sexual differences failed to reveal anything striking. 



Eunaticina oldroydii Dall. Fishermen, etc. None were dredged 

 by our party, though this mollusk seems to be a characteristic feature 

 of the Bay. 



Velutina Isevigata Linne. 12 fathoms ; one immature shell. 



Lamellaria rhombica Dall. 15 fathoms; living; one specimen. 



Acmaea asmi Middendorf. Not rare on the shells of the black 

 turban (Chlorostoma), but occurring nowhere else. Perhaps this is 

 a case of commensalism. 



