298 Dr Gairdner''s Observations during a voyage from 



In Lat. 47° S. and Long. 57° W., we met with a shoal of a 

 new species of Del phinus, allied in its piebald markings to theZ>. 

 leucoramphus, Cuv. R. A. i. 291, but in which the distribution 

 of the colours was different. Its high dorsal fin was of a black 

 colour, which was continued from its root into a band or girdle 

 encompassing the body. Tip of snout black, from which two 

 black bands proceeded to a circular band, one over occiput, other 

 along mesial line of lower jaw : ridge of back and belly behind 

 the dorsal band, also black ; all the rest of the body pure white. 



The Hydrostatic acalepha form an object of great interest to 

 the voyager in the Pacific Ocean. They often form shoals of great 

 extent ; in our passage from the Sandwich Islands to Columbia, 

 the ship sailed through one for about a week. The most beauti- 

 ful of these which I saw, as well as the most curious, from the 

 complexity of its structure, and the delicate arrangement of all 

 its movements, was the PhysaUa or Portuguese-man-of-war of 

 the English sailors, and I had an opportunity of verifying, on 

 numerous living and dead individuals, the accuracy of the 

 immortal Cuvier's brief notice in his R. A. iii. 285. Time 

 would fail me, and I would run the risk of exhausting y^our 

 patience, if I entered into a full detail of the many interesting 

 phenomena observed on the Chelonia, fish of the species of the 

 great family of Scomberoides, Squali, &c. observed on the voyage. 

 I will merely stop to mention a fact a little curious in the physio- 

 logy of the common Boiiito, the Scomber pelamys, Cuv. R. A. ii. 

 198, (N. B. the longitudinal black bands are not by any means 

 limited to four.) During many hundred miles of the voyage, the 

 ship was accompanied by numerous shoals, swimming with great 

 velocity close to the surface of the water, over the ship's quarter, 

 and occasionally presenting to the eye their brilliant silvery 

 bellies. When they turned for an instant on their sides, the vigour 

 and precision of their movements was beautiful. Although packed 

 close together, none interfered with his neighbour, although 

 often enveloped in the foam caused by the ship, and the break- 

 ing of the waves. They seem to feel peculiar pleasure in thus 

 coursing along in the agitated water of the ship's way ; it is not 

 from hunger, or in the expectation of food, for they will not 

 touch the bait of a hook. What can be the attraction ? The 

 following theory suggests itselt. Fish are known to respire only 



