178 



Professor Agassiz alluded to a remarkable feature in the distribu- 

 tion of the fresh-water fishes of Europe : that the fishes of the head- 

 waters of the three great rivers, the Rhine, the Rhone, and the 

 Danube, were the same, while those the lower waters differed not 

 only from one another, but also from those of the sources. 



Mr. F. W. Putnam remarked that the fresh-water fishes of North 

 America were generally more limited in their distribution than the 

 mollusks mentioned by Mr. Binney, although there were several spe- 

 cies that extended over the whole region from Texas north to the 

 Saskatchawan, and east to the Atlantic. Perca Jiavescens, Pomotis 

 vulgaris, and Boleosoma Olmstedii, are examples. The more limited 

 districts or faunae, within this region are, 1st, The waters of the 

 Upper Mississippi and Missouri; 2d, the Arkansas and its tributa- 

 ries ; 3d, the Lower Mississippi and south-west to the Rio Grande ; 

 4th, the waters of the Southern Atlantic States; 5th, the Ohio and 

 its tributaries ; 6th, the Northern Atlantic States ; 7th, the Great 

 Lakes, including, in all probability, Lake Champlain and some of the 

 larger lakes in Maine. 



Mr. Putnam was led to the supposition of there being a " Great- 

 Lake" fauna from the study of the Catostomi and Cyprini, having 

 carefully compared specimens of several species from Lake Richard- 

 son and Lake Champlain with those of Lake Superior, and found 

 them identical. 



Of the fishes of the Pacific slope of the Rocky Mountains he could 

 say but little, except that so far as he knew they were specifically 

 distinct from those of the Atlantic slope. 



With the exception of a well-marked Arctic fauna, the fishes north 

 of the States are not sufficiently known to warrant any conclusions. 



Mr. S. H. Scudder, in referring to Mr. Binney's remarks, said that 

 the study of the geographical distribution of insects in America did 

 not prove the boreal portions to be one indivisible province, but that 

 different species were found to inhabit the extremes and the centre 

 of the district. He alluded further to the European character of the 

 Lepidopteran fauna of California, where, in antagonism to the other 

 portions of America, there were found to be a great abundance of 

 Lyccenidce, and an almost total absence of Teriades. 



Professor Agassiz observed, from the dissimilarity of results arrived 

 at in the different groups, that too much confidence should not be 

 placed in conclusions obtained from a study of a single group only. 



Dr. O. W. Holmes exhibited a microscope-stand for which 

 he claimed certain advantages, and which he employs in his 

 demonstrations : — 



