274 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



5. Head very long and slender; dark brown or purplish, paler on 

 borders of cephalic furrows and tip of head; cephalic furrows 

 remarkably long and deep longiceps 



5. Head of moderate proportions, or short 6 



6. Body of moderate proportions 7 



7. Body very large and stout, sometimes becoming 2 m or more in 

 length and 25 mm in width; head and cephalic furrows short; 

 dark reddish brown herculeus 



7. Slaty brown to grayish or pale olive, paler beneath, with con- 

 spicuously paler or white lateral margins .... marginatus 



7. Color highly variable; pale yellow, bufif, light brown, or choco- 

 late brown; lateral margins thin and often pale; lateral nerve 

 cords red californiensis 



8. Rather slender; pale gray with numerous fine, irregular, and 

 much interrupted dark olive-brown longitudinal lines extending 

 whole length of body both above and below, but more numerous 

 and larger on dorsal surface than ventrally .... lineolatus 



8. Rather short; with conspicuous narrow band of dark color in 

 median dorsal line, and a series of narrow transverse markings 

 of dark color placed side by side on dorsolateral aspects of body 

 signatus 



38. Cerebratulus albifrons Coe, 1901 



C. albifrons Coe, 1904, 1905, 1905a. 



Habitat. In mud or beneath stones at low-water mark and below to 

 a depth of 100 m or more. 



Distribution. Coast of Alaska, Puget Sound, Monterey Bay, and 

 southward to San Diego, California. Dredged of? central and southern 

 California. 



39. Cerebratulus californiensis Coe, 1905 

 (Plate 24, figs. 7-11) 



Individuals of this species vaiy greatly in color according to age, state 

 of sexual maturity, and habitat. Young individuals are pale grayish, 

 pinkish, or yellowish, with a distinctly darker cephalic area (Figs. 8, 12). 

 When living in black mud the color is usually very dark brown or green- 

 ish brown, sometimes with distinctly lighter lateral margins (Figs. 9, 10). 

 The nerve cords and, to a less extent, the muscle layers are conspicuous in 

 life, because of a diffusible red coloring matter. 



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