COMPARATIVE ANATOMY 



CHAP. 



dseum, rd) stretches to the most anterior end of the body, to emerge 

 generally separately from the oral aperture in front of and above it. 

 The whole proboscidal apparatus is entirely separate from the intestinal 

 canal. The rhynchodseum thus leads through the proboscidal aperture 



^ 



f=^ 



B 



-rm 



-rsh 



Fig. 131.— Diagrammatic.representation of the proboscidal apparatus of tlie Nemertina. Jl, 

 Proboscis withdrawn. B, Proboscis protruded, r, Proboscis ; rs, proboscis slieatli ; rsTi, cavity of 

 the latter ; &i, stylet ; (/rf, poison gland ; rm, retractor muscle ; rrf, rhynchodgeum. 



into the central cavity of the proboscis which closes blindly behind. 

 The wall of the long proboscis is extremely muscular, the arrangement 

 of the fibres being occasionally very complicated. It is internally 

 lined ■\vith epithelium which is continued on to the rhynchodseum. 



