THE GLOW-WORM NERELS. 531 



The Lug- worm has some of the habits of the tube-making annelids, for, although it is 

 perfectly free and able to move where it likes, it does not push its way through the sand at 

 random, but forms a tunnel of moderate strength, through which it can pass and repass at 

 pleasure. As it bores its way through the sand, it pours out a small quantity of the glutinous 

 matter which has already been mentioned in the Terebella, and thus cements the sides of the 

 tunnel together in a manner somewhat resembling the brickwork of a railway tunnel. Like 

 that work of engineering skill, moreover, the tube of the Lug-worm cannot bear removal, 

 breaking up when it is unsupported by the surrounding earth. It is, however, amply strong 

 enough for its use, and will withstand the beatings of ordinary waves without yielding. 



In the whole of the genus Arenicola there are no eyes nor jaws, and the head is not distinct. 

 Several species of this genus are known. 



The Great Eunice (JSunice gigantea) is another annelid closely allied to the Nereidaj. 

 In this family the body is very long and composed of numerous segments. The proboscis has 

 at least seven, and sometimes nine pairs of horny jaws. Sometimes it will attain a length of 

 more than four feet, and comprise upwards of four hundred segments in its body, each segment 

 furnished with its paddles, some seventeen hundred or more in number. 



When in a living state, this is a most lovely creature, winding along its serpentine course 

 with easy grace, and gleaming with all the colors of the rainbow as the sunbeams fall on its 

 polished surface and active propellers. 



An example of the beautiful genus Nereis is now given. The Nereida? have both tentacles 

 and eyes, and the joroboscis is large, often being furnished with a single pair of horny jaws. 

 In the typical genus the eyes are four, arranged in a sort of square, and the tentacles are four 

 in number. The proboscis is thick, strong, and armed with two jaws. 



The beautiful Nereids are found plentifully on European coasts, mostly hiding under 

 stones and rocks, or hiding in the sand. They are well worthy of examination under the 

 microscope ; and, perhaps, the best method of making out the structure of these beautiful 

 creatures is by taking a single segment and noticing its construction. On the back are seen 

 certain tufts of different shapes in the various species, but all agreeing in being composed of 

 numerous blood-vessels ramifying in a most complicated manner. These are the gills, or 

 branchiae, of the Nereis. 



On each side are s< j en the organs of locomotion, sometimes consisting of a single, but 

 mostly of a double, row of oars. Each oar is formed of a strong muscular footstalk, from the 

 extremity of which proceeds a bundle of stiff bristles and a variously formed flap, which is 

 technically called the "cirrus." If the bristles be examined separately, their wonderful 

 forms cannot fail to attract admiration. They no longer appear as the simple hairs which the 

 naked eye would assume them to be. but are transformed, as it were, into a very arsenal of 

 destructive weapons, the barbed spear — the scimetar, the sabre, the sword-bayonet, and the 

 cutlass, all being represented ; while there is no lack of more peaceful instruments, such as 

 the grapnel, the sickle, and the fish-hook. 



The Nereids will live for a time in a shallow basin half filled with sea water, and. are, 

 therefore, valuable to those who really desire to study for themselves the beautiful forms with 

 which they are surrounded, and which, but for the microscope, would ever be hidden from 

 our eyes. The observer should not fail to examine the formidable proboscis with its terrible 

 jaws. While the worm is at rest, this proboscis is retracted like the finger of a glove, and the 

 jaws appear to be situated in the neck, where, indeed, they were once taken for a gizzard. 

 But either by dissection or applying pressure in the right direction, the jaws can be drawn 

 out, and are then found to be destructive weapons at the end of the proboscis. Many years 

 ago, while examining, for the first time, a Nereis which I had found on the sea-shore, I took 

 this structure for a gizzard, and find, on reference to my note-book, that a sketch of these 

 internal jaws is marked with the title, "Gizzard of the above." 



There are very many species of these interesting worms, among which we may mention 

 the Glow-worm Nereis {Nereis noctiluca), a little species seldom more than an inch in 

 length, but which is remarkable for its power of emitting jdiosphorescent light in a manner 



