A Pleurobranchus has been taken under stones at mid-tide near Cres- 

 cent City, California; field experience is the only guide in separating it 

 from its white nudibranch neighbors. Pedipes and Truncatellas live close to 

 high tide line on decaying eelgrass, a foot or more down in the rubble. On 

 the Mendocino County (California) coast the orange-colored animal of 

 Fusinus harfordi distinguishes it from white- animaled Searlesia dira much 

 more quickly than the shape of the shell. Opalia insculpta (O. crenimar- 

 ginata) usually lives in sand around the base of a solitary anemone. The 

 more northern O. chacei seems to be a mid-tide shell, sometimes in sand- 

 floored runways between ledges, again, especially in northern California, 

 in tidepools around purple sea urchins; live shells are apt to look gray- 

 green. Epitonium tinctum lives among anemones that grow in sheets cov- 

 ering the upper surface of rocks; some collectors find that running their 

 fingers through these masses causes their hands to become sore. 



Commensals. Melanellids are commensal; I have taken a few on a big 

 "sea lemon," but they occur in quantity in the sand beneath a little white 

 "sea cucumber" which in turn lives in hollows in the ledges near Crescent 

 City. Vitrinella oldroydi and Serridens oblongus live on or under large 

 Ischnochitons. 



Mussel colonies. The masses of Mytilus californicus that grow on pil- 

 ings or rocks frequently yield interesting shells of other species; various 

 Odostomias, Entodesma saxicola and Mopalias of certain color patterns are 

 frequently so found on northern rocks. An occasional Lamellaria sharonae, 

 a small pink form of Venerupis staminea, Odostomia, and Isapis fenestrata 

 (long thought to be scarce) are more apt to be found among the southern 

 mussels. Because of the so-called red tide the law forbids using either 

 mussels or clams for food or bait during the summer months, so one should 

 be prepared to convince a game warden that only specimen shells are 

 being taken. 



Limpets, Acmaeas are plentiful on our coast, and their specific varia- 

 tions and apparent intergrades are frequently described as a short cut to 

 insanity; where and how they live often helps to identify them. A. triangu- 

 laris lives on coarse coralline at Pt. Pinos; A. ochracea is apt to be on small 

 stones in the tidepools which do not go completely dry. Superficially it 

 resembles both A. patina and A. limatula, but the former is larger and lives 

 higher up on the beach, while the latter, also larger stays closer to tideline, 

 and is rare in the more northern range of A. ochracea. A. instabilis has a 

 very definite situs, the stem of one certain kelp; and watch for the prettily- 

 marked young. A tide of minus one foot is usually needed for this species, 

 or a swim suit and mask. It is not found south of Monterey. A. incessa 

 has its own ecologic niche, the long midribs of a Fucus; sometimes the same 

 plant will have A. incessa on the long floating ribbons and A. pelta on the 

 holdfast. A. persona seems to prefer shaded spots. 



Shell Clubs. Finally: try to get to a shell club meeting. That is the 

 best place to meet local collectors who will gladly supplement these sug- 

 gestions and help identify previous finds. Meantime, good hunting! 



(8) 



