JOHNSON : POLYCHAETA OF PUGET SOUND REGION. 
399 
14. Nereis vexillosa Grube. Pis. 3 and 4, figs. 31-38. 
Nereis vexillosa Grube. Middendorff’s Reise, etc., bd. 2, Zool., 
th. 1, 1851, p. 4. Taf. 2, figs. 1, 5, 6. 
n aretica Grube. Ibid., p. 11. Taf. 1, fig. 7. 
Ileteronereis middendorffii Malmgren. Ofversigt af k. vet. akad. 
forhandlingar, Stockholm, 1865, p. 109. 
This species, described and figured a half century ago by Grube, 
and subsequently by Ehlers (’68, p. 573), is one of the commonest 
Annelids all along the coast, from the Pribylof Islands to Santa Bar¬ 
bara. It apparently abounds in Puget Sound, judging from the 
fact that it occurs in all the collections from that region, and numer¬ 
ously in that of the Columbia Expedition. It is known to fisher¬ 
men as the “pile-worm,” on account of its habitat amongst the mus¬ 
sels and barnacles which cluster thickly upon the piles of wharves 
and bridges, and is in much requisition for bait. Upon the piles it 
seldom attains a length greater than 20 cm. and a diameter of 12 mm.; 
but in'gravelly beaches, where it lives in company with N. virens, 
it grows to a somewhat larger size. Olive-green is its usual color 
in life, but this changes to a bright emerald-green or bluish green in 
alcohol. Tints of brown are very frequent in the more posterior 
parts, and sometimes the entire worm is brown or dusky. 
The great dorsal lobe of the feet of the posterior portion of the 
body, carrying at its distal end the dorsal cirrus, increases notably 
in length with age, as may be seen by comparing Figs. 34 and 35, 
PI. 4. The former represents a foot of a young female; the 
latter, the foot of a large, sexually-mature female. This great 
increase in length is probably not correlated with the advent of 
sexual maturity, as some individuals of very diminutive size have 
the dorsal lobes of considerable length. In passing caudad the 
dorsal lobes lengthen so gradually it is impossible to find a demarca¬ 
tion-point between. long and short lobes. In the anterior region 
in front of the 12th foot the feet are of the form shown in Fig. 31, 
PI. 3 (tenth foot). 
The Heteronereis (epitokous form of Ehlers) is not uncom¬ 
mon (Figs. 32, 33). This condition is by no means confined to full- 
grown worms, but occurs in individuals having a length of 56 mm. 
and upward. The species also arrives at sexual maturity without 
becoming heteronereized, as I have noted in many instances. 
15. Nereis agassizi Ehlers. PI. 4, figs. 39-45. 
Nereis ac/assizi Ehlers. Die borstenwiirmer, 1868, p. 542. 
PI. 23, fig. 1. 
