62 



ZOOLOGY 



The position of the tentaculocysts, however, always marks the 

 position of the eight original lobes. 



Aurelia is a Scyphomedusan very commonly met with round 

 our coasts swimming at the surface of the sea. If the adult 

 medusa be examined, it will be seen that the original four-lobed 

 chamber of its Scyphistoma has given off a number of branch- 

 ing enteric canals which ultimately open into a circular vessel. 

 Between these canals the aboral and oral endoderm has given 



Fio. 43. — Awelia aurita. 



1. Mouth. 6. An adradial canal. 



2. Circumoral perradial processes. 8. The circular canal. 



3. Tentacles on the edge of the umhrella. 9. Marginal lappets hiding tentaculo- 



4. One of the tranching perradial canals. cysts. 



There are four of these, and four 11. Gastral filaments, 

 similar interradial canals. 



rise by concrescence to the endodermal lamella (Fig. 39). 

 Eight adradial canals are given off from the central chamber 

 between these branching canals, and these pass directly to the 

 circular canal without giving off any branches. 



The mouth of Awelia is surrounded by four perradial 



