460 On the Embryology o/Ophiocoraa echinata. 



structures, but consist in an epithelium of flattened cells, as 

 is shown by tigs. 4 and 5, which are camera drawings of 

 sections of two larvse. Fig. 4 represents the seventeenth, 

 twentj-first, and twenty-fourth longitudinal sections of a 

 young larva, the seventeenth section passing through the edge 

 of the alimentary canal and left pore-canal, the twenty-first 



Fi-. 5. 



/ pc 



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being the median sagittal section and passing through the 

 month and anus, the twentv-fourth cutting the larva in the 

 plane of the riglit pore-canal. Fig. 5 is a transverse section 



Fiff. 6. 



through the oesophagus of a slightly older larva cutting both 

 pore-canal openings. 



