49 



EXPLANATION OF PLATE VII. 



Structure of Anthozoa. 



Fig. 1. Trans, sec. of Siphonactinia triphylla, through region of 



oesophagus, i.e., cut along the line indicated by the letters 



A B in Fig. 3. X 3J. 

 Fig. 2. Trans, sec. of same, at a lower level, i.e., along line indicated 



by C D in Fig. 3. X 3J. 

 Fig. 3. Diagram of anemone structure, shown by a vertical section 



along the plane indicated by letters A B in Fig. 1. 



A mesentery is cut through longitudinally on the left 



side ; on the other, the section passes through an inter- 



septal space. 

 Fig. 4. 8. tripliylla, actual size. 



Fig. 5. Surface section through a colony of Alcyonium digitatum, 

 the polyps retracted wholly. For the sake of clearness, 

 the tentacles which are retracted within the oesophagus, 

 are omitted from the section. D, dorsal region ; V, ven- 

 tral region. X 9. 



Fig. 6. Trans, sec. thro' portion of stalk of a colony of A.palmatum. 



Lettering : cce, coenosarc ; cr, mesenterial filament or craspedon ; 

 dm, dorsal directive mesenteries ; dm, ventral ditto ; e, ectoderm of 

 body walls ; e, ectoderm of oesophagus ; en, endoderm ; gg, genital 

 gland ; im, intraseptal chamber ; is, interseptal chamber ; ip, inner 

 pore ; Im, longitudinal muscle band ; m, margin ; 2 m, secondary 

 mesenteries ; o, mouth ; op, outer pore ; ov, ovary ; ov', loose ovum ; 

 pbm, parieto-basilar muscle ; pm, primary mesenteries ; pr, peristome ; 

 rm, radial or transverse muscle fibres ; si, siphonoglyph ; sm, sphincter 

 muscle ; sp, spicules ; st, stomodseum or oesophagus : t, tentacle ; 

 tp, tentacle pore. 



