110 THE NAUTILUS. 



The writer proposes to figure the forms later. I may say that 

 Mr. Ford concurs with me in the arrangement of varieties here offered. 



The entire series of American Canjchium is closely allied to C, 

 viinimuvi of Europe, and doubtless sprang- from the same circum- 

 polar stock. 



NOTES ON Ml. HEMPHILL'S CATALOGUE. 



BY CHAS. T. SIMPSON. 



In a late number of The Nautilus the editor^ called attention 

 to the catalogue of shells recently issued by Mr. Henry Hemphill, 

 (in which he has made a considerable reduction in the number of 

 species) and asked for the opinions of students throughout the 

 country. As Mr. Hemphill is known to all to be a most careful 

 collector, and a close observer of the facts connected with the lives 

 and surroundings of Mollusks, such a reduction by him of the 

 number of our hitherto acknowledged species is, as has been 

 remarked, rather startling, and is, on account of the prominence of 

 its author entitled to at least careful consideration. 



It seems to me that the time is near at hand for quite a change in 

 our ideas concerning the classification of the forms of organic life 

 and their variations. The old idea which has so long prevailed, 

 that species were formed by an act of creation, fixed and unchange- 

 able, as coins are stamped out at a mint ; that genera and higher 

 groups have an invariable limit, is fast becoming obsolete, and we 

 are being daily forced by stubborn facts to learn that variation is 

 the rule and fixity the rare exception, that the limits of species and 

 the higher groups of forms are very often vague, or so absolutely 

 uncertain as to be impossible to define. By far the greater num- 

 ber of scientists believe in the theory of evolution in some form or 

 other, and hold that all the existing animals and plants are but the 

 direct descendants of other and extinct species, that the infinite vari- 

 ation which is found is caused largely by environment and other 

 circumstances connected with the life of the organism. In the Uni- 

 ted States we should expect to find an excellent field for such varia- 

 tion. 



1 The article on Mr. Hemphill's Catalogue to which allusion is made was not 

 written by the Editor. It was contributed by the officers of the American 

 Association of Conchoiogists. — Ed. 



