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Figs. 9 and 10. Cross-sections through a small portion of a swimming-plate 

 from the ctenophore, Mnemiopsis leidyi. The filament arrangement is 9 + 3 rather 

 than 9 4- 2, as there is a compact centre filament close to the two tubular ones. Two 

 of the nine filaments in the outer ring are connected to the ciliary membrane by a 

 ridge, visible as a line from these lateral filaments to the ciliary surface. The 

 arrows in P'ig. 9 point to places between the ciliary membranes where there can 

 be seen a bridging substance joining the cilia. These bridges are close to the 

 attachments of the ridges. Magnifications 125 000 and 105 000 x , respectively. 



