INDUSTRIAL PROGRESS DURING THE YEAR 1874. cxxxvii 



Professor Baird for the birds and mammals, who had shown 

 that they decrease in size southward. In insects the size 

 increases southward. Professor Band's law of increase in 

 length of the peripheral parts westward, extended by Allen, 

 also obtains in the Lepidoptera. In the family of Phalami- 

 dce, or geometrid moths, Dr. Packard finds that the Western, 

 i. e.,the Coloradian and Pacific coast individuals have a great- 

 er expanse of wing, and often more pointed ones, than in the 

 same species from the New England States. He also finds 

 that the variations from the Eastern type occurs in the same 

 species found in the Alps. A curious analogy is shown to 

 exist between the moths of the Colorado plateau and the ele- 

 vated region around the Ural and Atlas mountains, and the 

 plateau of Asia Minor ; certain generic types occurring in 

 those regions not found elsewhere. These resemblances are 

 attributed to similar climates, tne amount of rain-fall in Col- 

 orado and adjacent regions being like that of Western China 

 and Amoor land ; while the rain-fall of the region about the 

 mouth of the Columbia River is nearly the same as that of 

 the southern side of the Alps. Some species of moths have 

 brighter and deeper colors westward than their eastern rep- 

 resentatives. He thinks that differences in climate are most 

 important factors in producing varieties and species. 



In this connection should be noticed the facts brought out 

 by Mr. J. A. Allen in regard to the varieties of American squir- 

 rels. It seems from his studies, based on very extensive ma- 

 terial, that Southern squirrels are more highly colored than 

 Northern ones ; Western specimens, from the dry plains, are 

 paler, more faded out, than Eastern ones ; Southern speci- 

 mens are also smaller than the Northern darker forms. Con- 

 sequently he divides the continent into five more or less well- 

 marked areas, characterized by certain peculiarities of color 

 variation in birds and mammals. N. J. Elwes has also pub- 

 lished an interesting essay on the distribution of Asiatic 

 birds, illustrated by an excellent map. 



The Chcdlenger has resumed her voyage through the ant- 

 arctic seas, her naturalists aboard sending home accounts of 

 the novelties discovered by means of the dredge and trawl. 

 They have found a considerable number of species common 

 to the two poles, and greatly extended our knowledge of 

 the deep-sea fauna, which at great depths seems remarkably 



