[Reprinted from Twenty-Second Annual Report of the Fishery Board for 
Scotland, Part ITT., published. August 29, 1904. | 
VII—ON SOME PARASITES OF FISHES NEW TO THE SCOT- 
TISH MARINE FAUNA. 
- By Tuomas Scott, LL.D., F.L.S. 
Plate XVII. 
CONTENTS. 
; PAGE 
Preliminary Note, . : ; C : : ; . 275 
Part I. Copepoda Parasita— 
Fam. Dichelestide,. : : : : : ‘ . 275 
Part II. Trematoda— 
Fam. Tristomatide, 278 
Part III. Note on a Post-larval Fish attacked hy I Podon 
Leuckarti, . 279 
Description of ‘the Plates, . ; ; Nn ne : é ee at OU 
PRELIMINARY NOTE. 
Some time ago Dr Fulton, Scientific Superintendent to the Fishery 
Board, kindly handed to me for examination aspecimen of T7ygon pastinaca, 
Lin., which had been captured in the Dornoch Firth on October 22, 1903. 
This specimen measured about 143 inches across the pectoral fins and about 
244 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 pastinace, 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. fommer 
collections, I founda specimen of Lernia 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 i in the order in 
which they are referred to above. 
PART I.—COPEPODA PARASITA. 
Fam. DICHELESTID2. 
_ Genus Hudactylina, van Beueden (1853). 
Ludactylina minuta, T. Scott. Pl. xvii, figs, 111. 
Description of the Female.—The length of the specimen represented by 
me drawing (fig.1), measuring from the forehead to the end of the furcal 
