698 THE SERPULA. 



any limbs, and retain the two halves of the egg-shell by means of a filament, which 

 fastens them to the body. After a little while they gain three pairs of feet, and then 

 are able to separate themselves from the egg-shell. At this period of their existence, 

 they bear a great resemblance to the larvae of some beetles. As they continue to grow, 

 however, the number of segments and limbs increase, so that they gradually lose their 

 resemblance to the beetle larvae, and attain the shape and form of their parents. 



THE Spirostreptes cinctdtus is a native of India, and sometimes attains considerable 

 dimensions, reaching a length of nine inches. It is of a rusty red color, in some indi- 

 viduals inclining to yellowish clay, and has a drab ring round the middle of each seg- 

 ment. The legs also have a ring of the same color round the middle of each joint. 



The large straight figure on the right hand of the engraving represents the Spirostreptes 

 annuldtipes. This is also an Indian species, and somewhat resembles the preceding, 

 except that its colors are much deeper ; there is a narrow black ring round the middle 

 of each segment, and each joint is broadly banded with the same color. There are 

 seventy-five segments in this species, when it has reached full age. 



ANNULATA. 



A NEW class of animals now comes before us. These creatures are technically called 

 Annulata, or sometimes Annelida, on account of the rings, or annuli, of which their 

 bodies are composed. They may be distinguished from the Julidae by the absence of 

 true feet, although in a very many species the place of feet is supplied by bundles of 

 bristles, set along the sides. The respiration is carried on either by means of external 

 gills, internal sacs, or even through the skin itself. 



In most of the Annulata the body is long and cylindrical, but in some it is flattened 

 and oval. The number of rings is very variable, even in the same species ; so vari- 

 able, indeed, that in some specimens of Phyllodoce laminsoa, no less than five hundred 

 rings have been counted, while others possess only three hundred. 



The group of worms which come first on our list is remarkable for the architectural 

 powers of its members. In order to protect their soft-skinned body and delicate gills, 

 they build for themselves a residence into which they exactly fit. This residence is in 

 the form of a tube, and in some cases, as in the Serpulae, is of a very hard shelly sub- 

 stance, and in some, as the Terebella, is soft and covered with grains of sand and 

 fragments of shells. 



The beautiful SERPULA is now very familiar to us, through the medium of marine 

 aquaria, its white shell, exquisite fan-like branchiae, and brilliant operculum, having 

 lived and died in many an inland town where a living inhabitant of the ocean had never 

 before been seen. 



The shell of the Serpula is tolerably cylindrical, very hard, white, and moderately 

 smooth on the exterior, though it is ridged at intervals, marking the different stages of its 

 formation. The size of the tube increases with the growth of its inmate and architect, so 

 that a perfect specimen is always very small at its origin, and much larger at its mouth. 

 The Serpula is able to travel up and down this tube by the bundles of bristles, which 

 project from the rings along the sides, and is able to retract itself with marvellous 

 rapidity. It has no eyes, and yet is sensible of light. For example, if a Serpula be fully 

 protruded, with its gill-fans extended to their utmost, and blazing in all its scarlet and 

 white splendor, a hand moved between it and the window will cause it to disappear 

 into its tube with a movement so rapid, that the eye cannot follow it. 



