66 THE LEECHES OF MINNESOTA 



in the Bulletin of the Museum of Comparative Zoology, Vol. 

 XXXVI, (1900) pp. 16 to 64, and one by Moore, The Hirudinea of 

 Illinois, in the Bulletin of the Illinois State Laboratory of Natural 

 History, Vol. V (1901) pp. 479-547. The literature lists included 

 in these two papers will enable one to ascertain the principal papers 

 in which North American Hirudinea have been discussed. 



Characteristic features in the anatomy or exterior have been 

 figured for all of the species, in most cases from Minnesota repre- 

 sentatives, but new species or those which have not been figured 

 previously are treated in greater detail. 



Of the biological relations of leeches to other animals much 

 remains to be learned and this field affords a rich opportunity for 

 exact observation. Likewise the breeding and other habits of many 

 species are unknown or known only imperfectly. The remarks on 

 this side of the subject which follow the descriptions are based on 

 observations made chiefly in the vicinity of Philadelphia. 



The .drawings of the frontispiece are colored from living ex- 

 amples taken, with the exception of Hccmopis grandis, near Phila- 

 delphia. 



