Arenicola niariua 101 



Colour. — Young specimens of Arenicola marina are almost pink 

 in colour, as the numerous Ijlood- vessels aie seen tluough the 

 translucent body-wall. The gills of such specimens are usually 

 bright red. 



Older specimens are darker, but their colour is very variable. 

 The amount of pigment is increased, especially at the anterior end of 

 the worm, which becomes brown or greenish, and in the tail, which 

 becomes yellowish gi-een, while the middle region remains of a pink 

 or light red colour. Some specimens finally become very dark — a 

 velvety greenish black — with l>eautiful metallic green and iridescent 

 sheen. The gills of these dark examples are generally also pigmented, 

 and thus have a reddish brown or black appearance. The colours 

 of typical light and dark examples are shown in L*late I, 

 Figs. 1 and 3. 



The amount of dark pigment present depends to some extent on 

 the age of the specimen, but the nature of the sand in which the 

 worm has been living seems to be a more important factor. It is 

 generally agreed that light coloured examples are found in almost 

 pure sand, while dark ones live in sand or mud containing much 

 organic matter. Light and dark specimens may l)e taken within a 

 comparatively short distance of each other, in the same beach ; but 

 it will generally l)e found that the dark ones show a predilection for 

 certain places where there is muddy, black sand, or, to state the 

 matter more correctly, the conditions in these areas produce dark 

 worms, while in a neighbouring clean patch of sand the worms are 

 liglit in colour. The two specimens figured in Plate I were taken 

 at the same time from the beach opposite Fisherrow, ]\Iusselburgh. 



Distribution. — Arenicola marina occurs in suitable situations on 

 the shores of western Europe as far south as Foz de Douro, Portugal. 

 It extends northwards to the extreme north of Norway, and it has 

 been found in the White Sea, off Cape Piagosin in the Kara Sea, and 

 on the west side of Spitzbergen, the last being the most northerly 

 definite locality for the species and genus. A. marina is present in 

 the western part only of the Baltic, lliigen being the most easterly 

 locality in which it h:is been found in that sea. It occurs at Trieste, 

 and possibly at other stations in the western ]\Iediterranean (see 

 p. 93) ; but its range of distribution in that area has not yet been 

 ascertained. This species is present in the Faeroes, and on the shores 

 of Iceland and Greenland, and extends down the east coast of 

 America as far as Noauk, Conn., which is apparently the most 



