296 



APHRODITICE.- 



-ANNELIDA.- 



-ArURODITID/E. 



twist themselves with violence as if they would fiighteu 

 away their foe by their contortions ; but these are weak 

 lesources in comparison with the protection they derive 

 from their panoply of spines and bristles, and it is 

 curious to remark that as these diminish in size and 

 piquancy, and become better adapted to locomotion 

 than ofl'ence, the worms, as if conscious of their defence- 

 less state, forsake the nomade life, and seek additional 

 security by digging themselves furrows for retreat in 

 the sand and mud." — {Johnston.) These bristles, which, 

 as stated above, can be retracted within the body and 

 protruded again at the will of the animal, are distin- 

 guished into spines (ackiili), and bristles properly so 

 called (festucw). The spines, or acimli, are stiff and 

 very resisting, and are distinguished from the bristles 

 by being larger and being placed in the centre. The 



Fig. 201. 



Spines of Aphrodita. 



bristles, or fcstucm, are various and vcrj' remarkable in 

 structure, and their uses are well wortliy of attention. 

 Did our space permit we could dilate at great length 

 upon this subject, but limited as we necessarily are, 

 wc can only refer to the writings of Audouin and 

 Milne Edwards, Oersted, Dr. Johnston, &c., for further 

 information, and to the accomi)anying illustrations 

 (fig. 201) of a few of their most interesting forms. 

 These figures are highly magnified, the weapons 

 themselves being extremely small though exquisitely 

 formed. Their number in some of this tribe of Anne- 

 lides is immense. Some species have been found to 

 possess five lurndred feet on each side. Each foot has 

 two branches, and each branch has at least one spine 

 and one bunch of bristles, some of them simple and 

 some of them compound. These individuals then have 

 two thousand spines at least ; and if we reckon ten 

 bristles to each brush, it has also twenty thousand of 

 them ! Not only are these spines and bristles of great 

 importance to the animal, they are also beautiful objects 

 to look at; for some even of these " laidly worms" shine 

 with a splendour truly remarkable. The ApJiroclHcs 

 for example, or " Sea-mice" as they are often termed, 

 have their bodies covered with bristles or hairs which 

 possess a brilliant metallic lustre. " Gold, azure, purple, 



and green play upon their surface in a thousand diDcr- 

 ent ways, and these colours, often iridescent, harmonize 

 perfectly with the ever-changing reflections of the rings 

 of their body. The wing of a butterfly lias not received 

 a more brilliant decoration than these worms concealed 

 at the bottom of tlie sea, and often hidden in black and 

 felid mud." — (il/. Edwards.) Cuvier was so struck 

 with this beautiful play of brilliant colours that he 

 says it does not yield in beauty either to the plumage 

 of the humming birds or the most brilliant precious 

 stones. 



MM. Audouin ami Milne Edwards, wdio have 

 studied the Annelides very carefully, divide this order 

 into eight families — I. AjihrodUidcc ; II. Amjiliino- 

 midcE ; 111. E-iiniddce ; lY . Nereiduhe ; N.Ariciidm; 

 VI. Pcripatidtc ; VII. Cluvtopteridce ; VUI. Areni- 

 colidcc. 



Family I.— APIIRODITID^ 

 {The Sea-niicc). 



The Sea-mice are of an oval, oblong, or linear- 

 elongate and depressed form, the body composed of a 

 definite number of segments, and the back covered 

 with a series of scales, or elytra, disposed in two rows. 

 The species belonging to this family are amongst the 

 most highly organized of all the Annelides. The head 

 is distinct from the other rings of the body, and pos- 

 sesses eyes placed on its vertex, generally foui in 

 number and arranged in two pairs ; true antennw, in 

 general to the number of five, sometimes three, 

 the odd one being placed in the centre ; a 

 cylindrical proboscis fringed with papillie round 

 the orifice and armed with four jaws united in 

 pairs, the two above and the two below having 

 their cutting edges placed opposite each other. 

 The feet are usually very distinct, well devel- 

 oped, and composed of two branches, each 

 furnished with a spine, with bristles, and with cirrhi. 

 These feet, however, are not uniform in structure, for 

 some are furnished with a supeiior cirrlius and usually 

 with branchiio, hut have no elytra, whilst others have 

 scales or elytra but want the cirrhi and branchite; 

 and these different kinds of feet alternate for a definite 

 ijpace along the sides. The branchia;, when present, 

 are only rudimentary and generally concealed. But 

 one of the most remarkable parts of the exterrial 

 structure of the Sea-mice is the existence of these 

 elytra mentioned above. These are large mem- 

 branous scales which form two rows placed longitudi- 

 nally along the back of the animal, and are fixed 

 to the base of the superior branch of the feet by 

 means of a short pedicle. They are formed of two 

 cutaneous or epidermoid layers, applied the one against 

 the other, but capable of being separated so as to become 

 vesicular, and, like the oviferous feet of the Ajms 

 amongst the Entomostraca, appearing at certain seasons 

 of the year to be filled with eggs. A certain number 

 of the feet are destitute of these scales, and, as stated 

 above, these feet alternate with those that are provided 

 with them — a peculiar structure which does not exist in 

 any other family of Annelides, and forming the leading 

 peculiarity of the present group, as well as one of its 



