196 



COLLEGE ZOOLOGY 



an anus that is posterior and dorsal; the mus- 

 cular system consists of an outer circular and 

 an inner longitudinal series. The sperms and 

 eggs are derived from mesoderm. Cleavage of 

 the egg is spiral unless obscured by excessive 

 yolk. Four classes are recognized as follows: 



Class 1. Polychaeta. Marine; parapodia well 

 developed and provided with setae 

 that are variously modified; prosto- 

 mium and first few segments some- 

 times highly cephalized; sexes usually 

 separate; larva typically a trocho- 

 phore. Ex. Neanthes virens (Fig. 

 99). 

 Class 2. Archiannelida. A small heterogeneous 

 group, most nearly related to Poly- 

 chaeta; therefore some zoologists pre- 

 fer to make it an appendix to the 

 class Polychaeta rather than give 

 it a separate class status. It is charac- 

 terized largely for loss of morphologic 

 characters such as distinct parapodia 

 or setae, and retention of larval ones 

 such as ciliary rows. Mainly marine, 

 littoral, and sometimes living in 

 brackish to fresh water. Usually dioe- 

 cious or sometimes hermaphroditic 

 larva, a trochophore, or development 

 direct. Ex. Dinophilus (Fig. 90). 

 Class 3. Oligochaeta. Terrestrial or fresh- 

 water; without parapodia, and setae 

 few; head not well developed; herma- 

 phroditic; no trochophore larva. Ex. 

 Lumbriciis terrestris (Fig. 90). 

 Class 4. Hirudinea. Parasitic or predaceous; 

 mostly fresh-water or terrestrial; with- 

 out parapodia or setae; body with 33 

 segments plus prostomium; posterior 

 and often an anterior sucker; herma- 

 phroditic; coelom reduced by en- 

 croachment of connective tissue. Ex. 

 Ilirudo medicinalis (Fig. 105). 



SELECTED COLLATERAL 

 READINGS 



Bahl, K.N. Pheretima, An Indian Earthworm. 

 Lucknow Publishing House, Lucknow, India, 



1947. 



Ball, R.C., and Curry, L.L. "Culture and 

 Agricultural Worth of Earthworms." Bull. 

 222, Michigan State Univ., East Lansing, 

 Mich., 1956. 



Beddard, F.E. "Oligochaetes (Earthworms, 

 etc.) and Hirudinea (Leeches)." Cambridge 

 Natural History. Macmillan, London, 1896. 



Bell, A.W. "The Earthworm Circulatory Sys- 

 tem." Turtox News, 25:89-94, 1947. 



Borradaile, L.A. and Potts, F.A. The Inverte- 

 brata. Cambridge Univ. Press, New York, 

 1958. 



Buchsbaum, Ralph. Animals Without Back- 

 bones. Univ. Chicago Press, Chicago, 1948. 



Darwin, C. The Formation of Vegetable 

 Moidd Through the Action of Worms, with 

 Observations on Their Habits. Murray, Lon- 

 don, 1881. 



Grove, A.}. "On the Reproductive Processes of 

 the Earthworm, Lumbricus terrestris.'' 

 Quart. J. Microscop. Sci., 69:245-290, 1925. 



Harvev, E.N. Bioluminescence. Academic Fress, 

 New York, 1952. 



Miner, R.W. Field Book of Seashore Life. 

 Putnam, New York, 1950. 



Moore, J. P. "The Control of Blood-sucking 

 Leeches, with an Account of the Leeches of 

 Palisades Interstate Park." Roosevelt Wild 

 Life Bull, Syracuse Univ., 2:1-55, 1923. 



Robertson, J.D. "The Function of the Calcif- 

 erous Glands of Earthworms." /. of Exper. 

 Biol. (British), 13:279-297, 1936. 



Stephenson, J. The Oligochaeta. Clarendon 

 Press, Oxford, 1930. 



Wilson, E.B. "The Embr\'ology of the Earth- 

 worm." /. of Morph., 3:387-462, 1889. 



