The royal natural history . such ascrustaceans. The figure of T. obscurum illustrates othercharacters in the anatomy of these animals. The twoswellings situated in the head end and united by a crossbridge constitute the brain or chief centre of the nervoussystem; running backwards from each to the hinder end ofthe body is a long nerve-chord, supplying the muscles andother organs of the body. The winding curled tubes, whichalso run the length of the body, arc the so-called water-vessels. These worms, which have received their generic name from the pre-sence of four eyes, are widely distributed,
The royal natural history . such ascrustaceans. The figure of T. obscurum illustrates othercharacters in the anatomy of these animals. The twoswellings situated in the head end and united by a crossbridge constitute the brain or chief centre of the nervoussystem; running backwards from each to the hinder end ofthe body is a long nerve-chord, supplying the muscles andother organs of the body. The winding curled tubes, whichalso run the length of the body, arc the so-called water-vessels. These worms, which have received their generic name from the pre-sence of four eyes, are widely distributed, most of the species being minute,and commonly found among seaweed. The worms of this group that havehitherto been discussed have the proboscis armed with stylets, and are consequentlycalled the Hoplophora, or armed nemertines. The second division, namely, theAnopla,—comprising those kinds which have no spines upon the proboscis,—containssome of the largest species of the class, Meckelia somatotoma reaching a length of. END OF PROBOSCIS OF Tetrastemma i enlarged . 45S WORMS. ? from 3 to over 6 inches. It is a long, flat, whitish-coloured creature, occurring onmuddy ground and between the branches of coral; and has received its name fromthe habit of breaking up into pieces at the least touch. Thevitality of the severed pieces is so great that the head end* w lias the power to re-form a new tail, and the tail end a new head, and the intermediate pieces a new head and common kind is Polio, crucigera, so-called becauseits greenish body is marked with five longitudinal whitebands and transverse white stripes, forming together aseries of crosses. These worms are long and slender, reachinga length of about 16 inches. The proboscis, moreover, whenprotruded, adds another 6 inches to their extent. They arefound most abundantly in pieces of rock riddled with holesand galleries by boring sponges, and they also intertwinethemselves amongst the prongs of branching-corals, as
Size: 1170px × 2137px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, booksubjectnaturalhistory, booksubjectzoology
