INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 487 



agilis,) wliicli it somewhat resembles in form. Tlie color is very variable ; 

 it is often bright yellowish green, but frequently dark green, brownish 

 green, or brown. 



The Nereis virens (p. 317, PI. XI, figs. 47-49) is very abundant in bur- 

 rows beneath the rocks. The males of this species, six to ten inches or 

 more in length, and of a dark green color, were found at Watch Hill, 

 April 12, in great numbers, swimming about in the pools of water among 

 the rocks, with an undulatory motion, and discharging their milt in large 

 quantities. Various other Annelids burrow or build tubes beneath the 

 stones. A.2)lanaria and LeiHoplana folium creep over their lower sur- 

 faces. 



Attached to the stems of Fucus at low-water, several Hydroids may 

 usually be found, but the Sertularia pumila (p. 327, PI. XXXVII, tig. 

 279) is by far the most abundant. The Obelia genicuJata is also very 

 common, attached to Laminar ia and other alga;. Various Bryozoa occur 

 attached to stones and to Fucus and other alga". The AJcijonidium 

 hispidum (p. 312) is one of the most abundant species, and usually in- 

 vests the stems and fronds of Fuous vesioulosusj but also often covers 

 broad surfaces of the rocks. The A. Mrsutum is often associated with 

 the preceding species on the rocks; it forms broad, thin, soft crusts, cov- 

 ered with small soft i)rominences, but is without the spines or bristles 

 seen in the latter. The Zooids are also much smaller. 



The Farrella famil laris is a singular and delicate species, which occurs 

 both on the under side of rocks and on algie. The body is small, fusi- 

 form, attached by a long and very slender, flexible pedicel. When it 

 surrounds the stems of small algne, the whitish pedicels project outward 

 in all directions, and thus produce the appearance of a delicate chenille- 

 cord. This is a northern and European species. It was also dredged on 

 Saint George's bank in 1872. 



List of species found on the outer rocJcy shores. 



ARTICULATA. 



Crustacea. 



Page. 



Cancer irroratus 486 



Cancer borealis 486 



Pauopeus depressus 312 



Panopeus Sayi 312 



Homarus Americanus. 492 



t 



Orchestia agilis 315 



Hyale littoralis 486 



Calliopius hieviusculus 315 



Gammarus ornatus. : 486 



Gammarus aunulatus 4S6 



Page. 



Gammarus marinus 486 



Ami)hithoe maculata 486 



Amphithoe, sp 486 



Caprella, sp 316 



Jtera copiosa 486 



Idotea irrorata 486 



I. phosphorea 316 



Erichsonia filiformis 316 



Balanus balanoides ... - 486 



