points, cind they are not homologous with the so-called Septal- 

 knoten, or areas of adhesion in the Peromedusae. The true co- 

 lumellae, or "Septalknoten" in the ■^eromedusae are separated, 

 according to Haeckel's figures, from the areas of adhesion by 

 spaces in which the gonaslia lie, and are the walls of the large 

 septal funnels where these pass throi:gh the stomach from the 

 subumbrella to the exumbrella. 



V/hile the septa are shrinking to become the coluraellae, 

 ridges appear opposite each other on walls of the peripheral 

 part of the digestive tract between the bases of the tentacles. 

 The entoderm at the summits of opposite ridges unites and thus 

 there is formed a series of lines of adhesion extending inward 

 from the periphery and dividing the space into a series of ra- 

 dial canals, each ending in a tentacle, whether it be rhopalial 

 or interrhopalial. The two disks of jelly never fuse along 

 these lines of adhesion but the entoderm remains between them 

 as the entodermal lajnella. or cathamjnal plate. At the stage 



of Fig. 40 the lines of adhesion occupy half the space from the 

 margin to the columellae. 



At this same stage eight curious nettle batteries appear 

 arranged s'^rametrically on the proboscis. Perhaps it would be 

 better to speak of them as special organs for the production 

 of nettle cells. They are nearly spherical thickenings of the 



- 48 - 



