80 



posited with that of the present. In Europe the opinion 

 has prevailed among geologists that at the epoch of the drift 

 the climate was colder than it is now. 



Beneath the oyster bank of Nantucket is a stratum of 

 coarse, sandy clay, very much like that at the base of the 

 cliff of Gay Head, which was regarded by Prof. Hitchcock 

 as a tertiary deposit. It is probable, therefore, that these 

 two formations are the outcrops of a Tertiary basin which 

 passes underneath these two islands of Nantucket and Mar- 

 tha's Vineyard and the intervening sea. 



Boulders are found on the surface of both of these islands. 

 It is an interesting inquiry how those on Nantucket could 

 have been deposited above the bed of fossils without disturb- 

 ing it. The regularity of the stratum of sand under them, 

 and the character of the climate as indicated by the shells, 

 are incompatible with an explanation based on the glacial 

 theory. They could hardly have been brought by Icebergs, 

 for among them are masses of Pudding-stone, such as exists 

 at Hingham and Roxbury, which rest here at a higher level 

 than their source. 



Prof. Agassiz gave an account of two new fishes obtained 

 by him at Lake Superior, which he regarded as the types of 

 two new genera. The first is an entirely new type in the 

 class of fishes. Prof. A. incidentally alluded to his former 

 researches, by which he had demonstrated the constant 

 relation existing between the character of the scales and the 

 general character of the fish, and mentioned some instances 

 in illustration. 



The first of these two new species is a small fish, five or 

 six inches long, in its general shape resembling a Leuciscus, 

 It has the adipose fin of the SalmonidcB, but not the jaws 

 of that family ; these strongly resembling those of the Perc- 

 oids. In its scales, which are serrated on their margins, it 

 also resembles the Percoids. Its characters are sufficiently 

 peculiar to justify the establishment of a new family from 



