314 



CCELHELMINTHES. 



primitive forms which in structure and development (fig. 273) are 

 of importance in the phylogenesis of the Annelids. Polygordius. * 

 ABO 



FlG. 284. New England Annelids. A, male Autolytvs ; B, Sternaspis fossor ; C, Cis- 

 tenides gouldii ; Z>, Clymene torquata. (From Emerton and Verrill.) 



Order II. Oligochaetae. 



The Oligochaetes are almost as preeminently fresh-water and 

 terrestrial forms as the Polychaetes are marine. They are in 

 most respects simpler than their marine relatives, apparently the 

 result of degeneration, which has followed from the more simple 

 conditions of existence. Eyes are rudimentary or lacking, they 

 have no palpi, cirri, or tentacles; gills are rare, but most striking 

 is the absence of parapodia, the bristles projecting directly from 

 the body wall (fig. 280). The chaetae may be regularly distributed 

 around each somite (Pericliceta) or gathered on the sides (Megas- 

 colex) or arranged in four bunches so that in the animal four 

 longitudinal rows occur. The animals are hermaphroditic, testes 

 and ovaries lying in different somites. Usually the integument in 

 the neighborhood of the sexual openings is thickened by the 



