LEPTOMEDUSAN MELICERTIDIUM OCTOCOSTATUM. 461 



Since the tentacles are often found inturned into the umbrellar 

 cavity, and even with their ends projecting into the mouth, we 

 may infer that their ciliation will also assist, however slightly 

 and intermittently, the important business of food gathering. 



So far as I know, the only author who has investigated the 

 direction of the ciliary currents in hydi'oid medusae is Boehm 

 (Jen. Zs. Natw. xii. 1878, p. 108), and what he states in this 

 connection is that the currents are always from stomach to ring 

 canal, and that he has not been able to make out ciliary, activity 

 in the roof of the latter. 



Reference may be made to the following recent papers on 

 ciliation in other marine animals : — 



Carlgren, O.— Biol. Centralbl. xxv. 1905, pp. 308-322 (Acti- 



nians, Madreporarians). 

 Orton, J. H. — Journ, Mar. Biol. Assoc. U.K. ix. 1912, pp. 144- 



478 (Ascidians, Molluscs). 

 Ortox, J. H. — Ibid. X. 1913, pp. 19-49 (Amphioxus, Ascidians, 



Molluscs). 

 Gbmmill, J. F.— Proc. Zool. Soc. Lond. 1915, pp. 1-19 (Starfish). 

 WiDMARK, E. M. p.— Zs. Allg. Phys. Jena, xv. 1913, pp. 33-48 



{Aurelia ciurita). 

 Gemmill, J. F. — Proc. Zool. Soc. Lond. 1919, pp. 263-265 



(Ctenophore). 



