MANUAL OF ZOOLOGY 



quently divisible into regions owing to more or less marked 

 differences in the development of the parapodia and other 

 points, between the anterior part which may be thrust out 



Fig. 115. — LumbricuS agricola. A, entire specimen, lateral view ; B, ventral view 

 of anterior portion of the body, magnified, /, 15, 33, first, fifteenth, and thirty- 

 third segments. The black dots represent the setae. (After Vogt and Jung.) 



of the tube and the posterior parts which habitually remain 

 enclosed in it. All the Polychaeta, with one or two ex- 

 ceptions, have the sexes separate, and have a free-swimming 



