12 Dr. W. NicoU on the 



Firth of Forth and forwarded to Professor M'lntosh, a large 

 number of specimens of this parasite were found. Stossich's 

 oiiginal description of the species is incomplete and contains 

 several errors, which were corrected by Loose's amended 

 description. My specimens differ in a few particulars from 

 those examined by Looss, and botli on that account and on 

 account of the comparative rarity of the species I shall give 

 here a fairly full description of it. 



]\Iy specimens are only half the size of Stossich's, measuring 

 for the most part from 1'8 mm. to 2"4 mm. They are ex- 

 tended and flattened, but the neck is somewhat subcylindrical. 

 The greatest breadth is a little more than ^ of the length and 

 occurs, as a rule, about the level of the ventral sucker, but 

 in many cases it is as far back as the anterior testis. From 

 this point the body narrows rapidly towards the anterior end, 

 but behind the sucker it preserves a fairly uniform breadth, 

 till near the posterior end, where it comes abruptly to a 

 j)oint; in some cases the posterior end is bluntly rounded. 

 Almost the entire surface is covered with spines, which show 

 much greater variations in size than is usual amongst spinous 

 Trematodes. Over the greater part of the body they are 

 long, curved, and sharp, with a fairly broad base, and, as 

 usual, they are largest and strongest just in front of the 

 ventral sucker. Forwards these large spines stop suddenly a 

 little in front of the pharynx, and their place is taken by 

 very much smaller spines of minute size. The large spines 

 advance further forwards in the middle line and at the ex- 

 treme edges of the body than elsewhere, so that the minute 

 spines appear to be congregated in two lateral patches, 

 united, however, in the middle line in front. Precisely the 

 same arrangement occurs on the dorsal surface, although in 

 this case the large spines are found a little further forward 

 than on the ventral surface. In the latter ])oint this differs 

 from Loess's description. In the arrangement of the cephalic 

 spines another difference must be noted. In addition to the two 

 series described by Looss, a third one occurs in many, though 

 not in all, of my specimens (PI. I. fig. 3). This is situated 

 on the dorsal surface a short distance behind the hind rows of 

 large spines, and consists of a row of about 10 straight sharp 

 spines, resembling the large spines, but only about half their 

 size (length '025 mm.). It is hardly necessary to be reminded 

 here that cephalic spines are only too prone to be knocked 

 off and disappear without leaving traces of their existence. 

 In the majority of my specimens the cephalic armature was 

 incomplete. iSuch must have been tlie case in Loess's 

 specimens, otherwise this third series of spines could not have 



