110 a. pennington's notes on a slide. 



which, in the oral disc, is not well developed, but which in the body- 

 wall forms a broad, well defined, powerful muscular system. 



The epithelial cells contain three series of elements— ciliated, 

 stinging, and glandular. In the tentacles the stinging cells, or 

 cnidcB, may be easily seen, as they are both large and numerous. 

 They are oval in shape, and each contains a spirally coiled ecthor- 

 aeum. The gland cells are very numerous in the body- wall, where 

 they are often filled with granular or colouring matter. 



The nervous layer consists of an interlacing network of fibrillse, 

 with here and there ganglion cells. 



The muscular layer is the most important layer in the Cerian- 

 thidce. In the tentacles the elements are isolated, but in the oral 

 disc it forms a distinct stratum, which, in the body-wall, becomes, as 

 stated above, broad and well defined. The longitudinal fibres com- 

 posing the stratum in the body- wall may be distinctly seen in the 

 slide. These longitudinal muscular fibres are supported by a thin 

 membrane, which springs from the mesoderm. 



The Cerianthi are able to secrete, or rather to form, an external 

 sheath or protective case of mucus mud, nematocysts, spicules, &c, 

 into which, when alarmed, they can retire. The powerful arrange- 

 ment of longitudinal muscles in the ectoderm of the body-wall is 

 necessary for this purpose. 



The mesoderm may be distinctly seen below the muscular layer, 

 and it will be seen to form, as it were, the basis or skeleton of the 

 body, as it runs through body-wall, oral disc, tentacles, septa, and 

 oesophagus. 



The endoderm contains two series of elements — muscular and 

 epithelial. 



Amongst the anemones generally the muscular layer of the endo- 

 derm is well developed ; the extraordinary breadth of ectodermal 

 longitudinal muscles, as seen in the slide, being peculiar to the 

 Cerianthidce. 



The muscular layer of the endoderm will be seen in the slide, 

 lying immediately below the mesoderm. 



The endodermal epithelial layer may be clearly made out, lining 

 the whole of the interior of the body. The separate cells, if isolated, 

 would be found furnished with a tuft of delicate cilia. 



In the accompanying slide the layers above described can all be 

 seen, and, in addition to the sections of the oral disc, a number 

 of sections of the tentacles will be found, some cut transversely and 

 others longitudinally. 



