PREFACE. IX 



press. Our obligations to other friends who have 

 assisted us with information or specimens are grate- 

 fully acknowledged in the body of the work. 



The drawings have, with some few exceptions, all 

 been prepared from recent specimens, examined by our- 

 selves, and wherever possible careful dissections have 

 been made.* There are a few species, however, of 

 which we have been unable to obtain specimens, such 

 for example as Demolens paradoxa, Lemseocera cypri- 

 nacea, Brachiella pastinaca, and perhaps one or two 

 others, figures of which have, with due acknowledg- 

 ment, been reproduced from published works men- 

 tioned in the sequel. In a considerable proportion of 

 the species dealt with in this work the ovisacs are 

 frequently greatly elongated, and we have followed 

 Dr. C. B. Wilson in adopting the term " egg-strings " 

 to describe them. The coloured figures of the para- 

 sites represent them as observed by us in the particular 

 specimen illustrated. The colours vary considerably 

 according to the condition of the parasite, the place 

 where it was attached, and the freshness of the host. 

 External parasites lose their colours much more 

 rapidly than those that are found under the oper- 

 culum or attached to the gills, and it is not always 

 possible to obtain perfectly fresh fish. 



THOMAS AND ANDREW SCOTT. 



ABERDEEN, 



31st March, 1913. 



* NOTE BY THOMAS SCOTT. The drawings and dissections referred 

 to above are entirely the work of my son Andrew Scott, who has 

 otherwise assisted in the preparation of the Monograph. 



