8 NATURAL HISTORY OF 



all the molluscs obtained, by far the most plentiful was an elegant 

 minute Dentalium, with a sharp marginal rim. Many of the 

 animals of this species were alive, and there was a regular 

 deposit of dead shells in the fine gray mud of the bottom. * 



We did our best to vary our term of imprisonment during 

 the two or three days following, which were very hot (the 

 thermometer 85 in the shade), by fishing expeditions, in 

 the course of which we captured one or two specimens of a 

 species of Caranx (probably C. dentex), several splendidly- 

 coloured wrasses {Lahridce), a small example of one of our own 

 British dogfish, and a young hammer-headed shark {Zygcena 

 malleus), which made its presence known to us by tugging 

 viciously at one of our lines, which it succeeded in breaking 

 as it was hauled up to the surface of the water. However, 

 apparently not having learned wisdom by experience, it 

 returned in a short time, and was again hooked, and this 

 time safely landed in the bottom of the boat, where it lay 

 flapping about, no one feeling particularly desirous of 

 handling it. I subsequently examined it with much interest, 

 as it was the first fresh specimen of this curious genus that I 

 had seen. Its length was 27 inches, and the breadth of 

 its extraordinarily-shaped head (measured from eye to eye) 

 6 J inches. After skinning it, I threw the carcase over- 

 board at one of the gangways, and immediately after became 

 the eye-witness of a most singular spectacle, for a swarm of a 

 species of fish, somewhat resembling a small bream in 

 shape, of a bluish-green colour above and silvery beneath, 

 and which we had observed constantly swimming about 

 the ship, but had not succeeded in obtaining, made their 

 appearance, flying upon the shark, and fighting most vigor- 

 ously for possession. As nearly as I could calculate the 

 number, there could not have been much fewer than a hundred 



