CTENOPHORES OF THE ATLANTIC COAST OF NORTH AMERICA 25 



Bolina elegans Mertens, 1833 (Mem. Acad. Sci. St. P^tersbourg, 

 Sci. Math. Phys. et Nat., sdr. 6, tome 2, p. 513, Taf. 6, fign. 1-4), from 

 the South Seas, is also pink in general color, but the upper parts of the 

 body are covered with numerous small papillae and these are absent in 

 the Florida species. B. hydatina of Chun is evidently the immature B. 

 vitrea from the Mediterranean. 



Fig. 7. — Bolinopsis vitrea. Adult, 1.25 times natural size. Show- 

 ing oral lobe expanded, and canals. Tortugas, Florida, June, 

 19 10. From life, by the author. 



A solution of 0.6 molecular sodium chloride inhibits and soon stops 

 the movements of the cilia of B. vitrea, but solutions of 0.4 molecular 

 magnesium chloride or molecular magnesium sulphate which are isotonic 

 with the sodium chloride of sea-water have an opposite effect, for they 

 produce an abnormally rapid movement of the cilia, each comb beating 

 independently, and the coordination of the rows of combs being destroyed. 

 In solutions containing potassium in weak concentration the combs stop 

 momentarily and then resume their movement. 



This converse relation between ciliary and muscular movement may 

 be explained in the following manner : When the muscles contract, the 



