EEPOET ON THE ACTINIARIA. 85 



to be products of the ectoderm (Annal. des Scienc. Nat., ser. vi. t. x. p. 78, 1879-80). 

 According to Jourdan, the papilla which he terms " verrues glandulaires " have ariseu 

 from the epithelium pushing its way like glands into the supporting substance, and be- 

 coming wholly or nearly detached into epithelial islands. The author gives these epithelial 

 cords as the first stage of development in longitudinal section, the detached epithelial 

 islands in transverse section. I have obtained figures exactly similiar to those given by 

 Jourdan, and am justified in the view that the constitution of the wall agrees in both 

 species of Bunodes, but am also justified in maintaining that Jourdan's view is erroneous. 

 These epithelial growths are linings of the depressions and furrows running on the surface, 

 of the wall ; they become deeply pleated during contraction, and may look like detached 

 epithelial islands in transverse section, whilst in longitudinal section they may be taken for 

 mere epithelial folds. In order to be quite certain, I made sections parallel to the surface 

 and also examined single papillae in transverse section ; in the former we have invariably 

 islands of connective tissue, the transverse sections of the papillae, surrounded by an 

 epithelial net-work but without glandular ducts ; in the latter the papillae proved to be 

 solid growths of the connective substance. From these observations I have already, in 

 the introduction, declared myself to be against the acceptation of the term " verrues 

 glandulaires." 



The circular muscle is entirely enclosed in the mesoderm, whi-ch, however, is only 

 slightly thickened by it ; the bulk of it extends longitudinally, is almost equal in breadth 

 the whole way along, and is separated from the endoderm by a narrow layer of connective 

 substance, from the ectoderm by a somewhat broader layer. The roundish bundles of 

 fibrillae, which merely consist of a few strong muscular fibrillse, are divided by processes of 

 connective substance into larger and smaller groups ; this is beautifully seen in the upper 

 part of the muscle, whilst there is a preponderance of small, irregularly distributed 

 bundles in the lower part. 



The muscles of the oral disk are divided into radial bands corresponding to the septa ; 

 they lie as a thickly folded layer in the ectoderm, like the longitudinal muscles of the 

 tentacles. Seventy relatively long, filamentous tentacles lie on the margin of the oral 

 disk ; they run out into a fine point, and project above the surface even in the contracted 

 animal. The outer tentacles are decidedly smaller than the inner. 



In order to observe the septa properly I cut out a quadrant of the body which I made 

 into transverse sections. From these it was plain that the directive septa running towards 

 the oesophageal grooves alone were perfect, and did not bear reproductive organs, whilst 

 all the other septa, not even excepting the principal septa, remain imperfect, and are 

 amply furnished with reproductive organs (testes). The differentiation of the septa into 

 muscular septa and reproductive septa, which is present in aU Sagartidae, extends in 

 Bunodes minuta to the more limited circle of the principal septa. 



If I may draw a conclusion from a small part of a single specimen, the formation of the 



