378 ON THE ANATOMY OF A SUPPOSED NEW SPECIES 



EXPLANATION OF PLATE XXXIV. 



Lettering used througJiout. 



ect. Ectoderm. end. Endoderm. s. tn. Structureless membrane or lamella. c. ect. 

 Calicoblast ectoderm. n. I. Nervous layer of the ectoderm. m. g. c. Mucous gland cells. 

 g. g. c. Granular gland cells. 7n. n. Mesenterial nematocysts. t. n. Tentacular nematocysts. 

 mus. Muscular fibres, ov. Ovum. m. J. Mesenterial filaments. »i. 1 Primary mesentery. 

 m. 2 Secondary mesentery, m. 3 Tertiary mesentery. 



Fig. 1. View of a large colony from the side (cleaned corallum). Nat. size. 



Fig. 2. A small colony from above. One parent and three daughter corallites. Nat. size. 



Fig. 3. A single calice from above. 1, 2, 3 Primary, secondary and tertiary septa. 



Fig. 4. Diagrammatical section of the ectoderm of the polyp outside the tentacles. 

 Mucous gland cells {m. g. c.) are everywhere numerous, but the granular gland cells 

 (g. g. c.) are only found near the base of the tentacles. Two kinds of nematocysts are 

 found, of which the mesenterial form («i. n.) is much the less numerous. The granular 

 nervous layer {n. I.) is not well marked except at the bases of the tentacles ; in it a few 

 large nuclei of nerve cells can commonly be distinguished. 



Fig. 5. Section through the body wall at the sphincter muscle, the fibres (mus.) of which 

 are small and flattened. No cell outlines can be distinguished in either the ectodermal or 

 endodermal epithelia. 



Fig. 6. Section through the middle of a single battery of nematocysts on one of the 

 primary tentacles. The central part of the battery is packed ^-ith nematocysts under which 

 the nervous layer is very conspicuous, while at the sides the ectoderm cells end in muscular 

 processes on the structureless membrane. 



Figs. 7 — 10. Tentacular nematocysts. (Oc. 4, oil immersion ~.) 



Fig. 7. A ripe tentacular nematocyst with the thread fully formed. Outside the basal 

 end is a conspicuous oval nucleus in a finely granular mass of protoplasm, which forms the 

 granular (nervous ]) peduncle. 



Fig. 8. A ripe tentacular nematocyst with the thread partially extruded, found lying 

 freely in the cavity of one of the retracted tentacles. 



Fig. 9. Developing nematocyst. In place of the extruded nematocyst a homogeneous 

 mass of protoplasm appears, the central part of which acquires a definite membrane and 

 becomes finely granular. 



