698 THE SERPULA. 



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 colour, in some individuals 

 inclining to yellowish clay, and has a drab ring round the middle of each segment. The 

 legs also have a ring of the same colour 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 colours are much deeper ; there is a narrow black ring round the 

 middle of each segment, and each joint is broadly banded with the same colour. There 

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



ANNULlTA. 



A NEW class of animals now cornea 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 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 variable, 

 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 Serpuke, is of a very hard shelly 

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

 fragments of shells. 



The beautiful SEEPULA 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 tra\el 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 splendour, 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. 



