Third, about twenty-nine miles from the island, 127 fathoms, bottom same as last haul. 

 Fourth, aboul forty-three miles from the island, 134 fathoms, bottom as in the last 

 two hauls. Fifth, about fourteen miles north of Keweenaw Point, 82 fathoms, two 

 hauls, reddish clayey mud and sand. 



North of Copper Harbor, August 2'2, dredgings were made at three different points : 

 First, seventeen miles oil', 1-1* fat hums, soft clay. Second, nearer the shore, 62 fathoms, 

 soft reddish mud and sand. Third, within a quarter of a mile of the shore, 17 fathoms, 

 sand. 



Off fifty miles on a course northeast by east, one-half north of Copper Harbor, August 

 24, 116 fathoms, soft clay. 



In Neepigon Bay, due north of St. Ignace station, and half a mile from the shore of 

 St. Ignace Island, August 28, 32 fathoms, very soft clayey mud. 



In the cove at the eastern end of St. Ignace Island, near St. Ignace station, August 

 29, 4 to 6 fathoms, sand with some mud, hits of wood, &c. 



About three miles south of the same cove, August 29, 73 fathoms, soft clayey mud. 



In a small harbor on the south side of St. Ignace Island, between the main island 

 and a smaller one, and due south of St. Ignace station, September 4, two hauls, 8 

 and 10 to 13 fathoms, a little sand and mud brought up with great quantities of the 

 same species of alga found at Simmons's Harbor, and which, according to Professor 

 Eaton, who has kindly examined it for me, is a small densely tufted species of Cladopliora, 

 possibly C. gl&merata Linn., a most variable species, but the specimens do not well 

 correspond with authentic ones from Germany. This alga was brought up in immense 

 quantities, the dredge being full at each haul. 



On a line between Michipicoten Island and Copper Harbor, and about thirty-seven 

 miles from the island, September 7, 147 fathoms, soft clay. 



From this list it is readily seen that, in all the deeper parts of the lake, the bottom 

 is covered with a uniform deposit of clay or clayey mud. All the soundings made by 

 the survey show the same thing, the specimens of the bottom brought up from deep 

 water by the lead being everywhere of the same character, varying only in color 

 and somewhat in the amount of sand mixed with the clay. The color was not uniform, 

 even in the same dredge-full, drab and bluish masses of the clay being frequently 

 mixed with brown or reddish lumps. In deep water, drab and bluish were the prevail- 

 ing tints, however. Water was taken from the bottom at many points, and was every- 

 where perfectly fresh. That from 169 fathoms gave no precipitate with nitrate of silver. 

 The temperature, everywhere below 30 or 40 fathoms, was very uniform, varying only 

 slightly from 39°, while at surface, during the season at which the dredging was carried 

 on, it varied from 50° to 55°. 



The fauna of the lake-bottom corresponds with these physical conditions. In the 

 shallow waters along the shores, the fauna varies with the varying character of the 

 bottom, while below 30 to 40 fathoms, where the deep-water fauna properly begins, the 

 same species seem to be everywhere nearly uniformly distributed down to the deepest 

 points. The soft clayey bottom is, however, very unfavorable to most forms of animal 

 life, and, as we might expect, the fauna of this region is very meager. Except among 

 the worms, it seems to have scarcely any species peculiar to it, and is characterized 

 rather by the absence of many of the shallow-water species than by forms peculiar to 

 itself. 



In the following notes upon the species obtained, I am indebted to Professor Verrill, 

 for the entire account of the worms. 



FISHES. 



Cottus Franlclini Agassiz. — Several specimens were taken, in 8 to 13 fathoms, among 

 Cladophora, &c, on the south side of St. Ignace. 



INSECTS. 



Chironomus, larva? and pupae. — Species of this, or of closely allied genera of small, two- 

 winged flies, were found in nearly all the dredgings. Several quite large whitish forms, 

 both larva? and pupa?, were common in all the dredgings down to 32 fathoms. A minute, 

 entirely blood-red species was found in 6 to 8 fathoms among the Slate Islands, and in 

 8 to 13 fathoms on the south side of St. Ignace. A slender, semi-trauslucent form was 

 found in inauy of the dredgings from shallow water down to 147 fathoms. 



An unknown dipterous larva, 4 to 6 fathoms, cove at the eastern end of St. Ignace. 



Ephemeridce. — The larva of a single species, 32 fathoms, Neepigon Bay. . 



Phryganeidce. — Two species, 8 to 13 fathoms, south side of St. Ignace. 



Hydrachna sp. — Taken in 4 to 6 fathoms in the cove at the eastern end of St. Ignace. 



