THE STRAIT OF MAGELLAN. 481 



the marine animals contained therein. We got under way 

 after our return on board, and proceeded northwards, occupy- 

 ing the day in a search for harbours, and entering many beau- 

 tiful inlets in the mountains, at the head of which extensive 

 glaciers and snow-fields were displayed. We returned to our 

 anchorage at the close of the afternoon, and the following 

 day passed southwards to Isthmus Bay on the western side 

 of the base of the Zach Peninsula. Finding this to be an 

 excellent anchorage, we remained to execute a survey of 

 it, and Dr. Campbell and I landed, and spent the afternoon 

 on shore, crossing the lowest portion of the narrow isthmus 

 from which the bay derives its name, and which connects 

 the Zach Peninsula, at one time evidently an island, with 

 the mainland. This we found had been employed as a port- 

 age by the Indians to Oracion Bay in Union Sound. We re- 

 mained at anchor throughout the 8th, to complete the plan 

 of the bay. The weather was tolerably fine, and accordingly 

 a small party spent the day in pulling about the bay, land- 

 ing now and then. Several flying steamers were observed, 

 one with exactly the plumage of the non-volant form, and 

 the others attired like the specimen obtained at the GaUegos 

 river. Two were shot, and I afterwards carefully examined 

 their skeletons, finding that the bones showed unequivocal 

 evidence of immaturity. On the afternoon of the 9th we 

 left the bay, and moved southwards to our old anchorage 

 among the Otter Islands. 



The 10 th was fair, though rather cloudy, and as we re- 

 mained at anchor a party of four of us borrowed the dingy in 

 the morning, and passed a very pleasant day in pulling about 

 among the islands. On this occasion, I was so fortunate as 

 to obtain specimens of three fine sponges, new to me, and 

 probably hitherto undescribed. All were of large size, and 



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