22 NATURAL ARRANGEMENT OP INSECTS. 



the earth-worm (Lumbricus) ; whilst they themselves 

 are preyed on hy birds, fishes,, and the aquatic larvae of 

 hexapod insects. The second family,, or Branchellio- 

 nidce, which have the hody furnished above with a 

 double series of membranous foliaceous appendages, is 

 formed by the single genus Branchellion, the typical 

 species of which attaches itself to the Torpedo in the 

 Mediterranean. 



(19.) The second large division of the group, the 

 ANNELIDES CHETOPODES, is considerably the most nu- 

 merous, and may be further separated into two sub- 

 divisions ; viz. the Annelides Cephalobranchice, or Tubi- 

 coles, and the Annelides Mesobranchice. The former 

 are without a head, eyes, or maxillae, and the body is 

 terminated anteriorly by a mouth. It is usually furnished 

 with appendages, the whole or the majority of which 

 are collected in front. It is also supplied with hooked 

 or subulated setae, which emanate from pediform tuber- 

 cles, and which enable them to ascend or descend within 

 their tubes. The majority can neither swim nor walk ; 

 and those which crawl upon the ground, do so by the 

 aid of their tentacula. These animals always reside in 

 tubes, which are affixed to other substances, and which 

 but few quit. Lamarck styled them sedentary, from 

 this circumstance; but very many which he arranged in 

 this division, from the animal being imperfectly known, 

 have, with the progress of research, been discovered to 

 belong to the gasteropodous mollusks, as Magilis, Ver- 

 metuSy Dentalium, Siliquaria, &c. : the habitations of 

 many of these animals are, consequently, very simi- 

 lar to those of the latter. The impervious nature of 

 their tubular residences required that their respiratory 

 apparatus should be collected at its orifice ; and we 

 therefore thus find their structure accommodating itself 

 to their natural economy. Several of these creatures 

 are gregarious, and their tubes then assume very much 

 the appearance of honeycombs. The animals them- 

 selves are elongate and vermiform. They consist of 



