PHYLUM ANNULATA 



5orj 



system and in the presence of ciliated pits ; but it has a row of comb- 

 like setie on each segment, and it has only a single [)aii' of nepliiidia, which are 



V.Nv.Cd 



i, 402. — Trochophore of Folygordius neapolitanus. A, lateral view of entire larva ; 

 B, diagrammatic vortical section ; C, transverse section throug-h. the plane ah in B ; An. anus ; 

 An. ci. anal cilia; Bf. blastocoele ; Br. apical plate; Ent. enteron ; Mad. meamlorm ; AI.-nL 

 hd. mesodermal bands ; Nph. head-kidney; Oc. oye-spnt ; Pr. or. ci. cilia of prutntroi.h ; Pre. 

 if 1,1. prnr'tiidiHinn ■,Pt.or. ci. pust-or.il cilia : St. ifui. stomodpeum ; V. Nv.C'd. ventral nerve-cord, 

 (From Parker's Biology, partly after Fi-aipont.) 



Pr.an.ci' 



An.ci 



Fig. 403.— Later stage in the development of Folygordius neapolitanus^ in which the 

 posterior part of the trochophore has become elongated and segmented; A, entire larva; 

 5, vertical section ; C, transverse section along the plane ah in B ; B^ — Z)'J, three stages in the 

 development of the somatic mesoderm : OA. coelotne : rul. Eptlnn. ciiiloniie epithelium ; l)er. 

 Ji'plhm. deric epithelium; M.pL mu sole -plate : Msd. (soni.), somatic mesoderm; Msd. (fipl), 

 splanchnic mesodcnn ; 0. eye ; t. tentacle. Other letters as in preceding figure. (From 

 Parker's Biology, partly after Fralpont.) 



situated in the peristomium. There is only a single (longitudinal) layer of 

 muscles in the body-wall ; the reproductive apparatus is not known. 



