x ADVERTISEMENTS, 
Walker Prizes in Natural History. 
The Boston Society of Natural History, 
offers a first prize of from $60 to $100 and a second prize 
of a sum not exceeding $50, for the best memoirs, in English, 
on one of the following subjects: 
1. The relations of inflorescence to cross-fertilization 
illustrated by the plants of eastern Massachusetts. 
2. What depths of formerly overlying rocks, now re- 
moved by denudation, may be inferred from the structure of 
various rocks in eastern Massachusetts ? 
3. Experiments affording evidence for or against the 
_ theory of evolution. 
Each memoir must be accompanied by a sealed envelope 
enclosing the authors name and superscribed by a motto 
corresponding to one borne by the manuscript, and must be 
handed to the Secretary on or before April 1, 1894. 
Prizes will not be awarded unless the memoirs are of 
adequate merit. 
SAMUEL HENSHAW, 
Boston, July 3, 1893. Secretary. 
