70 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



the U. S. Geological Survey, has, however, helped me in a number of 

 points connected with this branch of the subject. 



I am indebted to many friends for assistance. In particular, I wish 

 to acknowledge my deep indebtedness to Dr. C W. Stiles, of the 

 Department of Agriculture, for numerous judicious suggestions and 

 for encouragement and aid in very many ways, especially in the study 

 of the nuclei. M. Thelohan very generously placed at my disposal 

 notes on the synonymy of several species. The synonymy of the 

 piscine hosts has been revised by Dr. Theodore Gill. Finally, I desire 

 to thank the officials connected with the Library of the Surgeon-Gen- 

 eral, U. S. Army, for numerous courtesies extended me in the course 

 of a protracted examination of the valuable collections under their 

 charge. 



As far as possible, this paper has been brought up to January 1, 

 1894. Several subsequent papers have also been included (see pp. 

 128-129). 



