208 



COMPARATIVE ANATOMY 



CHAP. 



hnr 



Fig. 139. Organisation of an individual of 

 Plumatella repens, with protruded crown of tern 

 tacles. t, Tentacles ; lo, lophophore or tentacle car- 

 rier ; ts, tentacle sheath (wall of anterior body); to, 

 constant invaginated portion of the tentacle sheatM 

 Iw, posterior portion of body wall, covered with I 

 cuticular envelope (cell 2) ; au, anus ; ed, hind-gut ; 

 muscular (?) bands, which fasten the invaginated pal 

 of the tentacle sheath to the body wall ; rm, larger 

 retractor muscles for withdrawing the tentacle crow 

 into the cell ; /, funiculus ; st, statoblasts ; m, stomacB 

 with caecum ; Ih, body cavity ; g, brain. 



FIG. 138. Anatomy of Sipunculus with protruded proboscis, partly after Vogt and Jung ; 

 the body is cut open longitudinally, t, Tentacles ; g, brain ; vd, fore-gut ; rt, proboscis retractor ; 

 n, nephridia ; &mr, that portion of the ventral chord which lies in the proboscis and runs freely in 

 the body cavity ; bmrj, ventral chord of the trunk, marking the ventral middle line ; an, anus ; and, 

 anal glands ; ed, hind-gut ; nd, accessory intestine ; abd, descending limb ; aud, ascending limb 

 of the mid-gut. 



