NO. 13 COE : REVISION OF THE NEMERTEAN FAUNA 305 



8. Orange, yellow, brown, or brownish red, with narrow median 



white stripe T. bicolor 



8. Gray, yellow, green, or brownish green . . . . T. candidum 



84. Tetrastemma aberrans Coe, 1901 



T. aberrans Coe, 1904, 1905, 1905a. 



Habitat. Among hydroids and algae between tidemarks and below. 

 Distribution. At present known only from coast of Alaska. 



85. Tetrastemma bicolor Coe, 1901 



T. bicolor Coe, 1904, 1905, 1905a. 



Habitat and Distribution. At present known only from shallow water 

 near Kodiak Island, Alaska. 



86. Tetrastemma bilineatum Coe, 1904 



T. bilineatum Coe, 1905, 1905a. 



Habitat and Distribution. Among algae and other growths on rocks 

 and piers near low-water mark. At present known only from San Diego, 

 California. 



87. Tetrastemma candidum (Miiller), 1774 



T. candidum Mcintosh, 1873; Verrill, 1892; Burger, 1895, 1904; 

 Stephenson, 1911 ; Wheeler, 1934. 



Habitat. Among algae and other growths on rocks and piers near 

 low-water mark and below. 



Distribution. Circumpolar; Norway to Mediterranean to Madeira 

 and South Africa ; Labrador to southern New England and southward ; 

 Alaska, Puget Sound, Monterey Bay to southern California and 

 Ensenada, Mexico. 



88. Tetrastemma nigrifrons Coe, 1904 

 (Plate 31, fig. 42) 



T. nigrifrons Coe, 1905, 1905a. 



This species is highly variable both in color pattern and in pigmenta- 

 tion. Four of the most conspicuous color variations are indicated in 

 Fig. 42. Variety pallidum {a and d) is distinguished by triangular dark 

 brown marking on head and pale brown, buff, or flesh-colored body. 



