86 AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. 



The advantage of fixing upon some one variety as the typical form of a species is 

 this, — that the mind may have an initial term for the laws embraced under the 

 idea of the species, or an assumed centre of radiation for its variant series, so as 

 more easily to comprehend those laws. 



Again, abrupt transitions and not indefinite shadings have been shown to be the 

 law of nature. In proceeding from special characters to a general species-idea, 

 nature gives us help through her stepping stones and barriers. In former times, 

 man looked at iron and other metals from the outside only, and searching out 

 their differences of sensible characters, gradually eliminated the general notion of 

 each, by the ordinary logical method of generalization. But science now brings 

 the element to the line and plummet, and reaches a fixed numher for iron and other 

 elements as to chemical combination, etc. By this means, the studying out of the 

 idea of a species seems almost to have escaped from the domain of logic into that 

 of direct trial by weights and measures. It is no longer the undefined progress of 

 simple reason, with a mere notion at the end, but an appeal to definite measurable 

 values, with stable numbers at bottom, fixed in the very foundations of the 

 universe. So, in the organic kingdoms, where there is, to our limited minds, still 

 greater indefiniteness in most characters, the barrier against hybridity appears to 

 stand as a physical test of species. We are thus enabled in searching into the 

 nature of a species, to strike from the outside detail to the foundation law. 



The type-idea, as it presents itself to the mind, is no more a subject of defined 

 conception than any mathematical expression. Could we put in mathematical terms 

 the precise law, in all its comprehensiveness, which is at the basis of the species 

 iron, as we can for one of its qualities, that of chemical attraction, this mathema- 

 tical expression would stand as a representative of the species ; and we imght use it 

 in calculations, precisely as we can use any mathematical term. So also, if we could 

 write out in numbers the potential nature of an organic species, or of its germ, 

 including the laws of its variables, this expression would be like any other term in 

 the hands of a mathematician; the mind would receive the formula as an ex- 

 pression for the species, and might compare it with the formulas of other species. 

 But, after all, we have here a mere mathemathieal abstraction, a symbol for 

 amount or law of force, which can be turned into conceptions, only by imagining 

 (supposing this possible) the force in the course of its evolution of concrete 

 realities, according to the law of development and laws of variations embraced 

 within it. 



KEWER PLIOCENE FOS&ILS OF THE ST, LAWRENCE VALLEY. BX PROFESSOE DAWSON. 



■ The object of this paper was in the first place to notice sevei-al fossil shells 

 recently found by the author and others in these deposits, and which did not 

 appear to have been previously observed. The species mentioned were: 



Natica Heros, Say , Beauport. 



Natica Grcenlandica, Beck do. 



Fuiius tornaius, Gould. • Montreal. 



Fiisus harp^darius, Couthoy 



Rissoa, minuta Montreah 



Turritella, (like erosa) .............................. .Beauport. 



