226 



LOWER INVERTEBRATES. 



although variable in hue from reddish to orange and dark brown. From the head 

 spring very numerous flesh-colored tentacles, and three pairs of large feathered gills, 

 which are bright red from the blood showing through them. The tentacles are capa^ 

 ble of great extension, and may be stretched out to a length 

 of eight or ten inches. They are incessantly in motion, ap- 

 parently to gather food and materials for tube-building. This 

 species may b(? considered a type of the large family of Teeee- 

 BELLiD^, and possesses the following features characteristic 

 of the family : The body is thicker in front, the thin posterior 

 extremity bears no bristles ; the tentacles are filiform ; the 

 head is not marked off from the body ; the gills are confined 

 to a few anterior segments ; the bristles are short, those of 

 the upper row hair-like, of the lower, hooked. 



Eu-chone elegatis is a beautiful species found on the New 

 England coast. When expanded, the pale yellow or green- 

 ish branchiae are recurved and connected by a broad thin 

 membrane. The body anteriorly is reddish, changing into 

 flesh color and then into a darker green or brown as we pro- 

 ceed posteriorly. The species lives in water from five to 

 thirty fathoms in dt'pth, and makes slender tubes covered 

 with fine sand. 



In the large family of the Seepulid^ also, the gills are 

 confined to the anterior end of the body, and are covered 

 With cilia, which maintain a stream oi water, wlucn sweeps 

 food down towards the mouth, which is placed at the base of the gills. The head 

 is usually set off from the body by a collar ; all the bristles are hair-like, 

 except those on the anterior half of the lower row. Their larval life is 

 free-swimming, but when they settle down they excrete a calcareous 

 shell which the worms enlarge subsequently to meet the necessities of 

 the growing inhabitants. The secretion and shaping of the tube are 

 performed principally by the basal portion of the gills. The round, 

 crooked tubes made by the American Serpula dianthus are often found 

 on the under surfaces and sides of stones, and even in more exposed situ- 

 ations, — always near low-water mark. When disturbed, the worm sud- 

 denly withdraws its beautiful wreath of gills, and closes the aperture of 

 its tube with a curious plug, called the operculum, — the portcullis of 

 its castle. The branchiae, when fully displayed, reveal their elegance 

 of form and color ; they are a round cluster, parted into symmetrical 

 halves, some eighteen delicate feathered filaments on each side. The 

 colors are extremely variable, but always brilliant ; usually the brancliiEB 

 are purplish at the base, with narrow bands of light red or yellowish 

 green ; further from the centre the filaments are transversely banded 

 with purplish-brown, which alternates with yellowish-green ; in another 

 variety they are all citron'yellow, and in yet another all whitish, banded 

 with brown. 



Very different is the abundant Clymenella torquata, which is plain in 

 shape though pretty in color. It belongs to the Maldanid^, Polychseta in which all the 

 external appendages are very much reduced. Clymenella constructs long tubes of agglu- 



FlG. 220. — Clu- 

 menella tor- 

 qiiata. 



