an axis of jell.y in which there are transverse plates of great- 

 er aensity than tiie rest of the jelly, and these give the struc- 

 ture the cellular appearance first described by Hamann (1881). 

 The epithelium lining the funnels and tubes is ciliated. 

 I There open also into the brachial canals the li^mena of the 

 oral vesicles, (v. Fig. 26). These structures, as already 

 stated in the diagnosis, have their points of attachment in 

 the axils of the branches. All except the smallest are flat- 

 tened laterally. The smaller ones are oval in outline, the 

 larger ones linear. At one side near the apex there is a 

 cluster of short processes that Hamann has homologized with di- 

 gitella. 



The Oral Disk . 

 Although the eight oral arms seem to be placed at equal 

 distances and to be alike, they are morphylogically in pairs, 

 each pair being homologous to one of the four lips of an Aure- 

 lia, for example. The line tnat separates two members of a 

 pair is therefore according to Kaeckel's nomenclature a perra- 

 dius. The brachial canals from each pair of arms on entering 

 the oral disk converge and unite into a single tube that is 

 continued to the centre of the disk, where it unites with the 

 other three. In this way the course of the tubes on the oral 

 disk forms a pattern that resembles a I'laltese cross. At the 



16 - 



