PELAGIC ANIMALS, 27 



neighbourhood of Tristan da Cunha^ myriads of 

 these birds passed the ship to the westward^ appa- 

 rently coming from that island. A few da3rs 

 afterwards^ while 480 miles from the nearest 

 land, we caught a beautiful tern (^Sterna me- 

 lanorhyncha) hitherto considered to be peculiar to 

 Australia. 



On several occasions the towing net* produced a 

 rich harvest, especially one day when almost be- 

 calmed in lat. 34° 40' S. and long. 4° W. The 

 surface of the water was absolutely teeming with 

 marine animals. Of these a small Physalia and a 

 Velella (F. emarginata?) were the most plentiful. 

 The latter curious animal, consists of a flat oval 

 expansion, an inch and a half in length, furnished 

 below with numerous cirrhi and a proboscidiform 

 mouth, and above with an obliquely vertical crest, 

 the whole of a rich blue colour with white lines and 

 dots, the soft parts conceal a transparent cartilagi- 

 nous framework. The crest acts as a tiny sail 



* Not having seen a description of this useful instrument, 1 

 may mention that the kind used by Mr. Huxley and myself, 

 consisted of a bag of "bunting" (used for flags,) two feet deep, 

 the mouth of which is sewn round a wooden hoop fourteen inches 

 in diameter ; three pieces of cord, a foot and a half long, are 

 secured to the hoop at equal intervals and have their ends tied 

 together. When in use the net is towed astern, clear of the 

 ship's wake, by a stout cord secured to one of the quarter-boats 

 or held in the hand. The scope of line required is regulated by 

 the speed of the vessel at the time, and the amount of strain 

 caused by the partially submerged net. 



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