BARNES NORTH AMERICAN MOSSES. 



USE OF THE KEYS. 



Upon page 157 is a key to the four orders of Musci. The 

 first three orders each have a single genus only. To the 

 genera of the fourth order, Bryales, the key upon the fol- 

 lowing twelve pages is devoted. 



In this key there are always at least two choices pre- 

 sented, whose equivalence is indicated by similar numbers 

 or signs preceding the line, or by equal indention of the 

 lines, which usually begin with the same word or its op- 

 posite. When the second member does not follow on the 

 same page a reference to the page upon which it does oc- 

 cur follows the first. For an example see page 158. When 

 there are more than two choices offered, all except the first 

 and last are followed by a number or sign to indicate that 

 a succeeding one is to be sought. For an example see page 

 160. 



When the accepted choice is followed by a dotted line 

 leading to the name of a genus, the description of that genus 

 will be found in Lesquereux and James' Manual of the 

 Mosses of North America on the page indicated by Arabic 

 figures of ordinary face (999). The key to the species of 

 that genus will be found on the page of this work indi- 

 cated by the bold face figures (999) following. If the genus 

 be not described in the Manual it will be found described 

 in the Appendix, on the page indicated by italic figures 

 (999.) 



In the keys to species the correlative choices are indi- 

 cated in the same way. Arabic figures (999) following the 

 name of a species show that the species will be found de- 

 scribed in the Manual on the page named. If followed by 

 italic figures (999), a description will be found in the Ap- 

 pendix on the page indicated. 



APOLOGIA PRO LABORE SUO. 



No one realizes more clearly than the writer that such 

 work as that which is now presented -to students is in one 



