CNIDARIA 



115 



of tlie Scypliistoma tentacles and the gTowing out of the 

 margin of the peristome into a lobed crown consisting of 

 eight (four perradial and four interradial) mai'ginal lobes 

 (Fig. 56). Since the marginal lobes are not formed by the 

 outer 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 lobe-pouches (Fig. 

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

 develop three processes at their ends, of which the middle 

 one buds forth from the snb-umbrellar part of the 

 lobe at some distance fi-om the margin, 

 and becomes the sensory body \_Sinneskolbe^ 

 (sk), while the two latei^al processes bud 

 forth from the margin and become the alar 

 lobes. 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 lohe- 

 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 chaniber are very 

 close to each other, and these two walls 

 nowgrowtogether from the margin inwai'ds at sixteen regions 

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

 form sixteen radial fusions or concrescence-bands, which are 

 situated snh-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 anothei- 

 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. 50.— Strobila 

 polydiscaof Aurelia 

 aurita. On the up- 

 permost Ephyra the 

 Scyphistoma ten. 

 tacles in process of 

 desenerating. 



