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America, and had found many of them to be identical with those 

 found between us and Labrador. One shell in particular, iV^wci/Za 

 thraciceformis, he alluded to ; one valve of this shell brought 

 from Japan, exactly mated an opposite valve taken at Prov- 

 incetown, Mass. At Hakodadi, Japan, the Arctic fauna exists, 

 and some shells of our coast are found ; whilst at Simoda the 

 shells are those of the China seas. Birds can traverse the ocean 

 in the northern regions where the continents approach each other, 

 but it is a question if mollusca can travel such distances. 



Dr. Bryant stated that the majority of our Arctic birds are 

 identical with those of Europe ; and that the Arctic Ornithology 

 of the Western Coast of North America differs more from that 

 of the Eastern Coast than the latter does from that of Europe. 

 He also stated that the migration of birds is an interesting 

 subject bearing upon this question, the causes of migration being 

 by no means fully understood. This present winter, one of our 

 most common migratory birds, the Song Sparrow, (^Zonotrichia 

 meloda,) is quite abundant in the vicinity of Boston, and two, 

 which Dr. Bryant' killed for the purpose of examining them, 

 were fat and in good condition, showing that they had not suf- 

 fered from the severity of the weather, or the want of food, 

 causes generally assigned for the autumnal emigration of birds 

 from this region. 



Dr. T. M. Brewer stated that it had been ascertained that 

 there is a greater diversity of species among the birds of the 

 Eastern and "Western North Atlantic coasts than was formerly 

 supposed. Several species, bearing close resemblance upon the 

 two continents, have been established to be different — for ex- 

 ample, the Velvet Duck, the Peregrine Falcon, and the Fish 

 Hawk. It was interesting to observe that, for no apparent cause 

 in their organization different from that common to both shores, 

 many birds are found only on one or the other shore ; for in- 

 stance, the INIanx Shearwater, the lesser Saddleback Gull, the 

 European Scoter, (differing only in size from the American,) are 

 found only in Europe. Between the birds of the Atlantic and 

 Pacific coasts there is more diversity, and also there are observ- 

 able differences of distribution. Thus, Brunnich's Guillemot, 

 found by Dr. Kane in latitude 70° North, and rarely found so far 

 south as Massachusetts Bay, in midwinter breeds in the harbor 



