of the Fishery Board for Scotland. 275 



VII.— ON SOME PARASITES OF FISHES NEW TO THE SCOT- 

 TISH MARINE FAUNA. 



By Thomas Scott, LL.D., F.L.S. 



Plate XVII. 



CONTENTS. 



PAGE. 



Preliminary Note, 275 



Part I. Copepoda Parasita — 



Fam. Dichelestidai, . . . . ... . . 275 



Part II. Trematoda — 



Fam. Tristomatidas, ....... 278 



Part III. Note on a Post-larval Fish attacked by Podon 



Leuckarti, .......... 279 



Description of the Plates, ........ 280 



Preliminary Note. 



Some time ago Dr Fulton, Scientific Superintendent to the Fishery 

 Board, kindly handed to me for examination aspecimen of Trygon pastinaca, 

 Lin., which had heen captured in the Dornoch Firth on October 22, 1903. 

 This specimen measured about \ik inches across the pectoral fins and about 

 24i inches from the nose to the extremity of the very slender tail; it was 

 thus not more than about the average size of this kind of fish, yet it 

 yielded on examination no fewer than four different species of ectozoa. 

 Two of these species belong to the Copepoda and two to the Trematoda, 

 and only one of them, viz., Brachiella pastinacce, van Beneden, appears 

 to have been previously described. Descriptions and drawings of these 

 apparently new forms are given here. 



Moreover, while examining some organisms set aside from former 

 collections, I found a specimen of Lerncea lusci, Bassett-Smith, obtained off 

 Aberdeen in January, 1902 ; as this parasite has not before been recorded 

 from Scottish waters, I have had a short description, with drawings of it, 

 prepared for this paper. 



I have further to state that at the end of this paper will be found a 

 description and drawing of a very curious Natural History group consist- 

 ing of a larval fish, somewhat emaciated, and two small Crustaceans, which 

 appear to be attacking the fish ; for this interesting specimen I am indebted 

 to my friend and colleague, Dr Henry Charles Williamson. 



The drawings have been prepared by my son, Mr A. Scott, A.L.S. 



I propose to describe the various organisms mentioned in the order in 

 which they are referred to above. 



PART I.— COPEPODA PARASITA. 



Fam. Dichelestid^. 

 Genus Eudactylina, van Beneden (1853). 



Eudactylina minuta, T. Scott. PI. xvii., figs. 111. 



Description of the Female. — The length of the specimen represented by 

 the drawing (fig.l), measuring from the forehead to the end of the f ureal 



