ANNELIDES. 603 



dice, Aglaura and Oenone. 4. Amphmornee, including 

 Amphinome, Pleione and Euphrocine. 

 11. Destitute of antennce. No eyes. 



a. Body protected by an artificial tube. 



With the exception of the genus Clymene, in which the 

 branchiae are unknown, but supposed to reside in the fun- 

 nel-shaped termination at the anus, all the others belong 

 to the family Amphitritees of Lamark, consisting of Pec- 

 tinaria, Sabellaria, Terebella, and Amphitrite. 



b. Body destitute of an artificial tube. This includes 

 the genus Arenicola of Lamark, formed from the Lumhri- 

 cus mariniis of Linn.eus *. 



B. Aerating organs internal, in the form of lateral sacs,, 

 or unknown. 



1. Bodyjurnished with filaments^ or bristles, or spines. 

 In the genus Thalassina, distinguished by the subglobular 

 body and funnel-form mouth, the intestine is longer than 

 the body, and folded. In Lumbricus, the intestine is 

 straight -j*. The characters of the remaining genera of this 

 group, as Cirratulus, Nais, Stylaria and Tubifex, have not 

 been determined with any degree of precision. The histo- 

 ry of the genus Derris of Adams is equally obscure |. 



2. Body naked. 



a. One or both extremities furnished with suckers. This 

 includes the species of the Linnean genus Hirudo, now 



• Its structure is developed by Sir E. Home, Pliil. Trans, 1817, p. 2. 

 tab. iii. p. 1, 2, 3. 



•f The structure of the common earthworm is delineated by Sir E. Home, 

 Pliil. Trans, lb. Ihe L. vermicularh and rar?fga<«s of Muilek are com- 

 mon natives. 



X Lin, Trans, lii. p. fi?., Tab. xiii. fig. 1, 2. 



