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. Thélohan 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), 
