180 VOYAGES OF A NATURALIST 



the growth of kelp- weed, which grows in profusion 

 round the rocky islets in the Straits of Magellan 

 and Smythe's Channel. Amongst this weed they 

 obtain their food, which consists entirely of mussels 

 of two species.* Some of these mussels grow to 

 a large size, and we frequently found shells measur- 

 ing up to six inches in length. 



In Molineux Sound two examples of the diving 

 petrel were obtained. Other petrels are strong- 

 flying ocean birds, but this species trusts entirely 

 to its diving powers for means of escape when 

 pursued. Its flight is weak and short : the bird 

 soon drops back to the water and at once 

 dives. When skinning this bird, one cannot 

 fail to be struck by the curious formation of 

 the gizzard, which is soft and flabby, and is, in 

 fact, merely an enlargement of the proventriculus. 

 All those I examined were crammed with small 

 fishes. 



In each anchorage throughout these channels 

 a trammel net was set, and in most of the harbours 

 we had good catches of fish. By far the most 

 numerous appeared to be a species of grey mullet. 

 Small sharks were also caught and preserved, 

 while one specimen of Aphrites gobio was obtained 

 and brought home in spirits. This fish has an 

 enormous head, out of all proportion to its small 

 body. In the Straits of Magellan some large spider- 

 crabs were caught, several of which were as much 



* Mytilus magellanicus and M. patagonicus. 



