TRANSACTIONS 01' THE SECTIONS. 81 



selves so long out of the -water, aucl propelled themselves throuyli the air. The 

 results satisfactorily show that the ilyiugiish never leaves the water except pressed 

 by its aquatic enemies; aud with regard to the second point, although their 

 passage from the water to the air is always accompanied by a rapid vibration of 

 the pectoral fins, such a vibration does not continue, nor does it recur unless the 

 fish passes througli a wave-crest, or iu_^sorae manner wets its fins afresh. In this 

 case a new vibration occurs, and it seems the stimulus of the sea-water produces 

 the vibration in question. But the fish may progress with great rapidity for 70 

 or 80 yards, without any fresh vibration, although it never rises more than a foot or 

 eighteen inches above the surface of tlie waves. 



On Pelagic jloatlncf animals observed at Sea. 

 By Dr. Coxlixgwood, M.A., F.L.S. 



In this paper the author gave an account of observations upon the occurrence 

 and range of certain oceanic Mollusca, Ptcropods, compound Tuuicata, minute 

 Crustacea, &c., whicli he had met witli in a voyage of considerable duration, chiefly 

 "within the tropics. It was illustrated by specimens aud coloured drawings. 



Notes on Oceanic Hydrozoa. Bij Dr. C'ollingwood, M.A., F.L.S. 



The various species of Lucernariadie and PliysophoridiB formed the subject of this 

 communication. The author referred to the circumstances under which they occa- 

 sionally occun-ed in great profusion upon the surface of tiie ocean, usually all of 

 the same species, at the same time. Tlie shoals embraced, on different occasions, 

 Aiirelia, lihizostoma, PcUu/ia, Stcphanomia, PJit/salia, Vdclta, andPorpita. He espe- 

 ciallj' described the magnificent species of Plujsalia, seen in some abundance near 

 the Equator in the Atlantic Ocean, wliicli were each accompanied by a number of 

 small fishes, which harboured uuler the shelter of the long tentacles and polypites 

 of the P/ii/salia. 



On some remarhihle Marine Anim'ds observed in the China Seas. 

 By Dr. C'ollingwood, M.A., F.L.S. 

 The author stated that he had found many new species of Xudibrauchiata, Pla- 

 nariau Annelids, Crustacea, Echinoderms, &c. upon the shores of China, Formosa, 

 Borneo, and Singapore Straits, of which he exliibited specimens. He described 

 the habits of some remarkable crustaceans which iuhaljit the sandy shores of 

 these countries, and exhibited some new species of snapping shrimps (Aljjhens) 

 from Cliiua and Singapore. He announced also tlie discovery of some enormous 

 Actiniffi inliabiting tlie coral-reefs of the China seas, in which a number of fishes 

 lived semiparasitically. lie had met with these Actinire on tlie submerged reefs 

 of the Cliina seas, aud also upon tlie coast of Borneo, and had himself extracted a 

 living fish from one of tlieni. The paper Avas illustrated by a large series of 

 coloured drawings, made by the author, from life, the greater part of them being 

 of new species, to be afterwards described. 



On Trichodesraiiim, or Sea-dust. Bi/ Dr. Colling wood, M.A., F.L.S. 

 The curious little Alga remarked by former observers as discolouring the sea in 

 some parts of the world was observed by the author in greatest profusion in the 

 China sea, where it formed a thick scum of many miles in extent. It )iever pre- 

 sented the blood-red appearance of the two species of Trichodcsmium described 

 by Montague and others, but was always of a uniform pale straw-colour. The 

 JVutlior believed that it was a different species from T. Ehri'iihorgii ov T. Iliiidsii; 

 and stated that it was confervoid in character, exhibited no spontaneous movenicuts, 

 but was, in some parts of the Indian Ocean, associated with an Oscillatoria, which 

 he also described Avith figures. 



Professor Dickson exhibited an abnormal Leaf of P^wwhs hairo-eerasus, 



1867. 6 



