40 : Editors’ Table. [ January, 
ceived very much attention, we have endeavored to attract notice 
to what we have been accustomed to regard as the main factors in 
the extinction of species and of higher groups. That there isa 
limit to the age of species as well as to individuals almost goes 
without saying. As there is in each individual a youth, manhood 
and old age, so species and orders rise, culminate and decline, and 
nations have risen, reached a maximum of development and de- 
cayed. The causes, however complex, are, in the case of plants 
and animals, apparently physical; they are general and pervasive 
in their effects, and have been in operation since life began ; there 
have been critical periods in palzontological as well as geological 
history, and periods of rapid and widespread extinction as well © 
as a continual, progressive dying-out of isolated species. Such 
extinction was, so to speak, a biological necessity, for otherwise 
there would have been no progress, no evolution of higher types. 
“OF 
EDITORS’ TABLE. 
EDITORS: A. S. PACKARD AND E. D. COPE. 
In entering upon the twentieth year of the publication of this 
magazine, the friends of the undertaking may congratulate them- 
selves on its signs of good health and strength, as seen in the 
portly appearance of the later volumes. Having passed through 
the perils of infancy and childhood, may we hope that in entering 
upon years of maturity it will, with each volume, gain in strength © 
and character as an exponent of American natural science. 
While the magazine has doubled in size, the number of depart- 
ments and of assistant editors has correspondingly increased. 
More space is given to reports of scientific discoveries so as to 
render the magazine more useful to science-teachers, and the 
working naturalist. 
Our great need is, more numerous plates and cuts; to secure 
this end our friends are urged to aid in enlarging our subscription 
list. : 
_ Our hearty thanks are due to the public for its support, and to — : 
our contributors and assistant editors. Depending on their aid © : 
and good will we hope to make the future volumes of the Nat- 
URALIST still more deserving of public support and esteem, . 
é 
