CNIDARIA 



115 



the Scyphistoma tentacles and the growing out of the 

 margin of the peristome into a lobed crown consisting of 

 eight (four perradial and four interradial) marginal lobes 

 I^Hi^ig. 56). Since the marginal lobes are not formed by the' 

 ■^^xiter body- wall alone, but contain a corresponding diverti- 

 culum of the entodermal sac, the peripheral gastral chamber 

 in this way acquires eight blind sacs : the lohe-pouches (Fig. 

 58 /). The marginal or primary lobes \^Siammlappen\ soon 

 develop three processes at their ends, of which the middle 

 one buds forth from the sub-umbrellar part of the 

 lobe at some distance from the margin, 

 and becomes the sensory body \_Sinneskolbe^ 

 (sk), while the two lateral processes bud 

 forth from the margin and become the alar 

 bes. Inside of these are found the alar 

 ^pouches (Fig. 58 /) as prolongations of the 

 lobe-pouches ; in the sensory body also 

 there is found a prolongation of the gastral 

 entodermal layer, which is destined to pro- 

 duce the otolith crystals. 



The peripheral gastral chamber up to 

 this time was simple and undivided, and at 

 its periphery ran out into the eight lobe- 

 pouches. Since the disc of the developing 

 Ephyra is always flat, the upper and lower 

 (ex-umbrellar and sub-umbrellar) walls of 

 the peripheral gastral chamber are very 

 close to each other, and these two walls 

 now grow together from the margin inwards at sixteen regions 

 of the circumference [the shaded areas in Fig. 58], and thus 

 form sixteen radial fusions or concrescence-bands, which are 

 sitnated sub-radially (i.e. between the per-, inter-, and adradii). 

 In this way the marginal part of the peripheral intestine is 

 separated into sixteen marginal pouches (radial peripheral 

 pouches. Fig. 58 m), which are separated from one another 

 by the concrescence-bands (cathammata). Eight of these 

 marginal pouches are situated in the per- and interradii, and 

 are continuous with the lobe-pouches, while eight others 

 are adradial and interpolated between the former. In later 



Fig. 56.— atrobila 

 polydiscaof Aurelia 

 aurita. On the up- 

 permost Epliyra the 

 Scyphistoma ten- 

 tacles in process of 

 degenerating. 



