CTENOPHORA. 



197 



Verrill ; Leptopsammia Ed. and H. ; Endopsammia Ed. and H. ; Astroides Blainv. 

 (Fig. 155) ; Lobopsammia Ed. and H. ; PJiodopsammia Semper ; Rhizopsammia, Verr. 



Fam. 2. Madreporidae. Colonial, arising by gemmation from the j^des of 

 the parent polyp : coenenchyma more or less abundant, spongy and reticulate, 

 slightly or not distinct from the porous corallite-walls. Madrepora L. ; Turbi- 

 naria Oken ; Astraeopora Blainv. ;. Montipora Q. and G. ; Anacropora Ridley. 



Fam. 3. Poritidae. Sclerenchyma reticulate and perforate. Septa never 

 completely lamellary. Walls very porose. Corallites increasing by gemmation, 

 and united directly or by intervening porous sclerenchyma. Forties Ed. and 

 H. ; Synaraea Verr.; Napopora Quelch ; Ehodaraea Ed. and H. ; Alveopora 

 Q. and G. ; Dichoraea T. Woods. 



Sub-phylum II. CTENOPHORA.* 



Free-swimming, transparent pelagic coelen- 

 terata, with eight meridional rows of vibratile 

 plates formed of fused cilia. They possess 

 an oesopliageal tube called the stomach - 

 lined by ectoderm, and a gastrovascular 

 canal system. Nematocysts are almost 

 always absent. 



The fundamental form of the Ctenophora 

 is a gelatinous, spherical, or ovoid body, 

 which swims in the sea by the activity of 

 its ciliated plates. It has two poles the 

 oral pole marked by the mouth, and the 

 aboral pole marked by the sense organ. 

 The line connecting these two poles is the 

 main axis, and in describing the structure 

 of the body it is important to recognise two 

 planes which pass through this axis at right 

 angles to one another. The mouth leads 

 into a tube called the stomach (sometimes 

 called oesophagus or stomodaeum, because 

 it is lined by ectoderm), and the stomach 

 opens into the central part of the gastro- 

 vascular apparatus called the funnel (infuii- 

 dibulum). The stomach is furnished with 

 two hepatic bands. Both stomach and 

 funnel are flattened sacs, and both lie in 

 the main axis the funnel of course above 

 the stomach but with their long diameters 



FIG. 157. Hormiphora (Cy- 

 dippe) phtmosa (after Chun). 

 mouth. 



* C. Chun, "Die Ctenophoren des Golfes von Neapel," Fauna und Flora des 

 Golfes von Neapel. 1880. 



