720 Henry B. Ward, 



Detailed reference to her work will be made under the special 

 headings of this paper. 



Material. 



The fish were taken in salmon traps incidentally and was brought 

 to me at the cannery wharf. All of the rat-fish exarained were 

 infected with this parasite and each of them contained two para- 

 sites. The parasite was found in the spiral valve. save in one 

 case: a fish that had been left without examination for more than 

 a day owing to pressure of other duties; here one of the parasites 

 had already migrated as far as the stornach. Such migrations of 

 parasites after the death of the host are well known and have been 

 reported even for this form by Spencer. Watson, and others. Con- 

 ditions precluded making any extended observations on the living 

 animal. Those which were made confirm on the whole the records 

 of Lönnberg and Watson which are both extensive and complete. 

 Other investigators have made only casual observations on these 

 activities. 



The material obtained was preserved in corrosive Sublimate 

 with a trace of acetic acid, and in part was subjected to the method 

 of shaking devised by Looss (1901) and utilized with such success 

 by him and others. In this case the only result was to destroy the 

 external layers of cuticula and subcuticula and also the finer folds 

 of the rosette and lateral ruffles without bringing about the com- 

 plete relaxation of the powerfal muscalature so that the method can 

 not be regarded as valuable in dealing with these forms. 



Complete series of sections in various planes have been made 

 both in paraffin and in celloidin. Some portions have also been 

 reconstructed in the effort to secure positive evidence on obscure 

 points in the anatomy. 



Some of the apparent discoveries in regard to structural details 

 were so striking that I desired to compare my material first with 

 the long known European form and later with material that had been 

 studied by Watson. Trough the kindness of Professor W. N. 

 Parker, of University College, Cardiff, I received a dozen specimens 

 of Gyrocotyle taken from Chimaera monstrosa. In a collection sent 

 me for study by the U. S. Bureau af Fisheries is a single specimen 

 also. At my request Professor Kofoid kindly sent me last Sep- 

 tember specimens from the same locality as those on which Doctor 



