NO. 13 coe: revision of the nemertean fauna 295 



Genus ZYGONEMERTES Montgomery 



Three closely similar and possibly intergrading species of this genus 

 have been found on the Pacific coast. 



Key to Species 



1. Central stylet very short and stubby ; basis about 3 times as long 

 as stylet, with serrated posterior edge; 4-5 accessory stylets in 

 each pouch; 12 proboscidial nerves thalassina 



1. Central stylet moderately slender; basis about twice as long as 

 stylet, without sharply serrated posterior edge; 2-3 accessory 

 stylets in each pouch; 10 or 11 proboscidial nerves 2 



2. Color white or pale yellow albida 



2. Color whitish when young, becoming pale yellow, pink, orange, 



brown, red, or green when mature virescens 



62. Zygonemertes albida Coe, 1901 



Z. albida Coe, 1904, 1905, 1905 a. 



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

 tidemarks and below. 



Distribution. At present known only from British Columbia and 

 Puget Sound. 



63. Zygonemertes thalassina Coe, 1901 



Z. thalassina Coe, 1904, 1905. 



Habitat. Among algae and other growths on rocks and among broken 

 shells, low-water mark and below. 



Distribution. At present known only from the coast of Alaska. 



64. Zygonemertes virescens (Verrill), 1879 

 (Plate 30, fig. 39) 



Amphiporus virescens Verrill, 1879, 1892; Z. virescens Montgomery, 



1897; Coe, 1905, 1905a. 

 Examination of several hundred individuals representing all ages 

 shows that the species is extraordinarily variable in color, in arrangement 

 of ocelli, and in the relative proportions of central stylet and basis ( Fig. 

 39). 



