THE EAETH-WOEM. 707 



Sometimes this beautiful annelid attains a considerable size, reaching the length of five 

 or even six inches. Generally, however, from three to four inches is the measurement. It 

 is a slow-going, but very voracious creature, feeding even upon its own kind, and using its 

 powerful proboscis as a means of capture. 



In some species of this genus, the spines which edge the body are most marvellously 

 formed. They are set upon projecting footstalks, and when not required for use can be 

 drawn back into the body. Their shape, however, would seem to render such a proceeding 

 dangerous, inasmuch as they are formed just like the many-barbed spears used by certain 

 savage tribes. In the Aphrodite hispida, for example, they are just like doubly-barbed 

 harpoons, and would wound the soft tissues of the body most severely when withdrawn. 

 In order, therefore, to prevent this result, each spine is furnished with a sheath composed 

 of two blades, which close upon the barbs when the weapon is withdrawn, and open 

 again to allow its exit when it is protruded. 



THE second species represented in the above illustration is easily distinguished from 

 the preceding creature by the peculiar structure of the back, which is devoid of the felt- 

 like substance, and the scales are consequently bare. 



OH2ETOPTBRUS. Chcettipterus pergamentaceus. 



ON account of the singular structure of the CH/ETOPTERUS, it has been placed in a 

 family by itself, of which it constitutes the sole genus. 



This remarkable worm is one of the tube-builders, and makes a dwelling of a tough 

 parchment-like consistency, measuring eight or ten inches in length. It is found in the 

 seas about the Antilles. In this curious being there is no distinct head, and no vestige of 

 maxillse, but the proboscis is furnished with a lip, to which are attached two small 

 tentacles. " Then comes a disk with nine pairs of feet, then a pair of long silky bundles, 

 like two wings. The gills, in the form of laminae, are attached rather below than above, 

 and predominate along the middle of the body." 



THE next family, of which the common EARTH-WORM is a very familiar example, is 

 distinguished by the ringed body without any gills or feet, but with bristles arranged upon 

 the rings for the purpose of progression. 



In the well-known Earth-worm, the bristles are short and very stiff, and are eight in 

 number on each ring, two pairs being placed on each side ; so that, in fact, there are eight 

 longitudinal rows of bristles on the body, four on the sides, and four below, which enable 

 the creature to take a firm hold of the ground as it proceeds. 



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