PALEONTOLOGY. 147 



In identifying the various species by means of these 

 volumes we shall probably find some which are ap- 

 parently intermediate in their characters between two 

 nearly allied forms, and are thus difficult of certain de- 

 termination, since they might belong to either of the 

 figured species ; others, again, may vary more or less 

 from the particular type which happens to be figured. 

 Now it is often the practice in such cases to put these 

 -aside for duplicates, or even to throw them away alto- 

 gether, only inserting in the collection what are termed 

 -" typical specimens ;" but this mode of procedure is 

 reprehensible in the highest degree, since it tends to 

 confirm the old superstition that species are definite 

 -abstractions, and to draw hard L and fast lines between 

 -cognate forms which are unnatural and nonexistent 

 in reality. 



These forms ought, on the contrary, to be placed with 

 the species to which they are allied, and to be labelled 

 as a variety of that which they most closely resemble. 

 Had this always been done in private and public collec- 

 tions, we should now be in possession of many more 

 facts regarding the life-history of such forms than we 

 have knowledge of at the present time.* 



Besides these intermediate and somewhat indetermm- 

 .able forms, we may also discover some that do not 



* It will frequently be found that such intermediate forms 

 have been collected from intermediate beds, one of the allied 

 species being mainly found above, and the other below, the 

 horizon in which such middle varieties occur. It is unnecessary 

 to point out the bearing of this on Darwin's Theory of Evolution 

 {by descent with modification) ; every one who has read the 

 "Origin of Species" will understand it, and every one who has 

 not read that work should do so without delay. 



102 



