46 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 26 



Type: Holotype is E. Y. Dawson 8587, Dec. 20, 1949, in Herb. 

 A. Hancock Foundation. 



Type locality: Intertidal at —1.7 foot tide level, 2.5 miles north 

 of South Bluff, Isla Guadalupe. 



Additional material: D. 8227, dredged, 6-20 m., South 

 Anchorage, Isla Guadalupe. 



Working Key to the North Pacific Species of Ceramium 



1. Thallus completely corticated throughout 2 



1. Thallus with nodal cortication for the most part continuous, 

 but at least in some part with ecorticate internodal spaces, or 

 the cortex thin and loose over internodes 13 



1. Thallus with cortication only at the nodes, or with uninter- 

 rupted cortication only in older, lower parts or on reproductive 



branches 14 



2. Thallus bearing deciduous or persistent spines on apices 



or on short lateral branches 3 



2. Spines absent 4 



3. Sharp unicellular spines present at apices or terminating short 

 lateral branchlets C. horridum S. & G. 



3. Two or more multicellular spines terminating mature apices 



on main or lateral branches 



C. pacificum (Collins) Kylin (in part) 



4. Plants bearing conspicuous sickle-shaped swollen branch- 

 lets C. hypnaeoides 



(J.Ag) Okam. (Campylaephora hypnaeoides J. Ag.) 

 4. Plants without sickle-shaped branchlets 5 



5. Cortical cells, at least for the greater part, in distinct longitu- 

 dinal rows; with gland cells in the nodal cortex 



C. eatonianum (Farl.) DeToni 



5. Cortical cells not in distinct longitudinal rows; gland cells 



absent 6 



6. Plants large (10-15 cm.) with special whorls of fertile 



ramuli below C. boydenii Gepp 



6. Plants smaller, without special whorls of fertile ramuli 7 



7. Plants with penetrating, bulb-tipped, pigmented rhizoids 



C. codicola J. Ag. 



7. Plants without bulbous rhizoids 8 



8. Plants robust, the cortex 200 fx thick or more 9 



8. Plants not especially robust; cortex much thinner 10 



9. Plants creeping C. obesum Dawson 



9. Plants erect, epiphytic C. crassum Okam. 



(Campylaephora crassa (Okam.) Nakamura) 



