210 



Invertebrata there are none with nnore highly developed gills, as 

 they are called, than Crustacea. They are generally regarded as 

 appendages to the legs, but in reality they form an essential part 

 of them. In the lower orders of Crustacea the respiratory 

 fringes are attached to the last joint of the legs ; but higher up 

 in the series they approach nearer the body, and in the highest 

 of the class they are found on the hip joints. In fishes the gills 

 are placed on branchial arches, the inner surface being a por- 

 tion of the alimentary canal. In the higher Crustacea the 

 breathing apparatus consists of hollow cones, with numerous 

 little sacs branching from them in many rows, over the inner 

 surface of which the venous blood is distributed by a capillary 

 network of vessels. This venous blood is not sent/rom the heart 

 as in fishes but from a sac at the base of each gill, into which it 

 returns from the body. Having become arterialized it flows 

 into the heart from the gills. Thus in anatomical structure 

 and in function these organs are essentially different from those 

 known by the same name in fishes. 



Mr. Whitney gave an account of his labors during the 

 past summer as United States Geologist in the survey of 

 the Government lands on Lake Superior. 



The surveying party, he said, had confined their labors the 

 present year to the exploration of the mineral lands of that 

 region. He exhibited his maps, so far as they were completed, 

 of that country, showing the geography of the copper district, 

 and gave a brief outline of the geological formation of the 

 country between Lakes Superior and Michigan. The copper 

 district extends from Kewenaw Point to Montreal River. Nume- 

 rous old workings are found, usually in the richest veins, above 

 which trees are growing several hundred years old. Tradition 

 gives no account of the race which has left these traces of their 

 labors. At Minesota location, at the depth of fifteen feet from 

 the surface, a mass of copper has been found weighing seven 

 and a half tons, which had been raised from its position to the 

 height of two feet, by means of wedges, portions of which still 

 remain. The copper showed marks of the stone hammers used 

 by the miners, of which a large number were found in the 

 hole above the mass, more or less broken. These hammers 



