CNIDARIA 



109 



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P 



The structures occurring between these [eight] radii are 

 designated as adradial. 



The lower free margins of the four septa soon become 

 continuous with the wall of the central stomach in the form 



1^^ of four longitudinal folds, which ultimately extend through 

 ^Hthe entire length of the scyphopolyp, even into the foot. 

 ^'' These folds are known as the longitudinal folds, or tceniolce 

 (Fig. 52 F, t), and the sinuses of the central stomach limited 

 by them as gastral furrows. 



In the further metamorphosis of the larva the form changes, 

 approaching more and more the shape of a goblet (Fig. 53). 



Fig. 53. — Diagi-a-mmatic loTi<;itudinal section through a Scyphistoma (based on 

 Goettk). ^, perradial longitudinal section ; B, interradial longitudinal section; 

 pb, proboscis; f, tentacle ; tr, septal funnel ; m, gastral pouches; g, mesogloea; s, 

 septum. The entoderm is represented as a dark layer. 



The lower narrow portion is called the stalk or peduncle 

 (Fig. 55 st), the prolongation of the central stomach extend- 

 ing into it the peduncular canal. The upper part of the 

 body becomes flattened, and thus forms the oral disc or peri- 

 stome, in the middle of which rises the cone-shaped proboscis 

 (Fig. 53 ph) with its central four-sided mouth-opening. 

 The four corners of the mouth are placed perradially (Figs. 

 54 and 55). 



The first four tentacles now arise over the four gastral 

 pouches, and, in keeping with the successive appearance of 

 the pouches, those over the first pair of pouches arise first, 

 and then those over the second pair. A cylindrical ento- 



