XVI 



Figure 6. Transverse section of the end-bulb of the stalk, viewed from above, slightly magnified : a; transversal septum, and 

 the membraneous filaments, proceeding therefrom; bi connective tissue with its reticulating meshes. 



— 7- A similar section, lateral aspect: a) transversal septum; b reticulating connective tissue; c; the space under the 



free margin of the transversal septum, into which the dorsal and ventral canals open. 



— 8. Transverse section of the stalk, magnified: a) connective tissue; b) spicules; c) prolongations of connective tissue; 



d) a canal; e) longitudinal muscles on wall of canal; fj a narrow layer of connective tissue; g) circular muscles; 

 h) entodermic cells. 



— 9. Transverse section of a polyp, systematically represented, magnified: a) wall of the body, in which are seen 



spicules; b) entodermic cells on the outer wall of the oesophagus; c) in the anterior half of the oesophagian wall; 

 d) a septum; e) a chamber. 



— 10. A fragment of the inner wall of the oesophagus, highly magnified: a) epithel; b) unicellular glands (?). 



PI. XIII. 



Figure i. Leptotilum gracile, varietas norvegicum, natural size. 



— 2. Same animal, magnified; a) a polyp, with its cell. 



— 3. Calcareous skeleton, magnified. 



— 4. A polyp with its cell, magnified: a) spicules from the aboral surface of the tentacles. 



— 5. Polyps, magnified. 





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