XI 



Explanation of the Plates. 



Figure 



PI. I. 

 I. Duva rosea, natural size. 



— 2. A branch of the same animal with its divers ramifications, highly magnified: a' division of the main branch; 



b) 4 or 5 branchlets; c) 4 or 5 stalks, bearing each from 5 to 7 polyps. 



— 3- A. polyp, magnified. 



— 4. A longitudinal section of 2 polyps, united at the base, magnified: a) the elliptic oral orifice; b) the oesophagus. 



— 5- A longitudinal section of the anterior part of the polyp-body, together with half of the oesophagus, highly 



magnified: a) outer epithelium 1 ectoderm) underneath which is a strip of connective tissue, whence proceeds 

 a septum; b) longitudinal muscular fibres on the septum, attached to the oesophagus; c) transversal muscular fibres, 

 also attached to the oesophagus; d) epithelial cells in the upper part of the oesophagus; e) epithelial cells Cento- 

 derm'i in the lower part of the oesophagus. 



— 6. Transverse section of a branchlet. magnified : a i prolongation of connective tissue (septum ; b, b 1 the two septula, 



bearing each two long gastral filaments; ci connective tissue with alimentary canals. 



— 7. Transverse section of a trunk, showing the septa and principal canals, natural size. 



— 8. Transverse section of a small part of a branchlet, highly magnified: a) a long gastral filament, borne by a septulum; 



b) transversal muscular fibres on one side of the septulum; c) longitudinal muscular fibres on the other side; d) the 

 inner epithel (ectoderm) ; e) delicate alimentary canals in the connective tissue; T constricted gastric cavit>' of a 

 polyp, filled with epithel. and corresponding to a delicate alimentary canal. 



— 9. Nutritive canals in the connective tissue of the septa, magnified. 



— 10. Transverse section of the medial part of a polyp, magnified: a) the outer epithel (ectoderm); b) connective tissue; 



c) a septum bet\veen the wall of the body and the oesophagus; d) the inner epithel 'entoderm), investing the 

 divers chambers. 



17- 



PI. II. 



The outer epithel (ectoderm) of the zoanthodeme of Duva rosea, magnified 650 times, drawn by Camera lucida. 

 The inner epithel (entoderm); equally magnified. 



A piece of skin from the lower part of the trunk of Duva rosea, in which are seen the closely-set spicules, 

 magnified. 



5, 6, 7, 8. The same spicules, highly magnified. 



A piece of skin farther up the trunk of Duva rosea, in which the spicules occur widely separated, magnified. 

 A spicule from the coenenchym on the lower part of the trunk in Duva rosea, highly magnified. 

 Corpuscles of connective tissue in Duva rosea, magnified 850 times, drawn by Camera lucida: a' offshoots con- 

 taining protoplasma. 



a, b, c, d) spicules from the anterior half of the body of a polyp on Duva rosea, highly magnified. 

 Transverse section of a group of polyps on Duva florida, with generative products, magnified. 



A piece of the trunk of Duva florida, together with a main branch and its ramifications, slightly magnified: 

 a) grooves on the trunk; b) a main branch; c; branchlets. with their ramifications, at the extremities of which the 

 polyps occur. 



A polyp from Duva florida, magnified: a) suture with the adjoining polyp; b' the series of spicules on the aboral 

 surface of the tentacles. 



A piece of skin from the lower part of the trunk in Duva florida. showing the spicules placed one upon the other, 

 magnified, 

 a. b, c; the same spicules, highly magnified. 



