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VII._-NOTES ON SOME TREMATODE PARASITES OF FISHES. 
By Tuomas Scott, LL.D., F.LS. 
(Plates VII., VIIL) 
One or two papers on parasitic Trematodes of fishes have already appeared 
in Part III. of the Annual Reports of the Fishery Board for Scotland, 
published in previous years. In the present paper four species, in addition 
to those previously published, are recorded, one of which appears to be 
undescribed.* 
TREMATODA. 
Fam. TRISTOMATIDE. 
Genus Calficotyle, Diesing (1850). 
CuHaracter.— Body thin, tolerably expanded; posterior sucker discoidal, 
nearly sessile, and provided with seven rays and two spines; the mouth 
without suckers. 
Callicotyle affinis, new species. Pl. VIL, fig. 1. 
The Trematode recorded here has a close resemblance to Callicotyle 
kréyeri, Diesing, found on various kinds of skates (Raza clavata, radiata, 
and batis), but one or two obvious differences prevent its inclusion in the 
same species, and as I do not know of any other to which it can be ascribed, 
the name Callicotyle affinis may be given to it. 
It differs from Cazlicotyle kréyert in size, being nearly one and a half 
times longer ; in shape it is broadly ovate, and the greatest width, which is 
near the middle, is equal to rather less than half the length ; the width of 
the posterior half does not vary much, but the anterior half becomes 
gradually narrower towards the bluntly rounded apex. 
The posterior sucker is transversely broadly ovate, the width exceeding the 
length by about one-fifth; the anterior margin is broadly and evenly 
rounded, but the margin opposite is flattened and somewhat sinuate. 
Interiorly this sucker has, like that of Callicotyle kréyert, seven submarginal 
compartments and a central one; the lowermost of the seven compartments 
is in the middle line, and has on each side a slightly curved tooth; the 
centre compartment is not round as it is in Callicotyle kréyerz, but trans- 
versely narrow. There are apparently no suckers at the anterior end, and in 
this respect it also agrees with Callicotyle kréyert. 
The length of the specimen represented by the drawing (fig. 1) is 9 mm. 
AHabitat.—Parasitic on the gills of Chimera monstrosa, Linné, captured 
in the North Sea, January 1910. Apparently rare. 
Fam. PoLysToMATID&. 
Posterior suckers more or less numerous. : 
Genus Octobothriwm, Leuckart (1828). 
Trematodes provided with eight posterior suckers and usually with a 
small one on each side of the mouth at the anterior end. 
-* I am indebted to my colleague, Dr. Williamson, for the privilege of examining 
the fishes on which the organisms recorded here were obtained, and to my son, 
Andrew Scott, A.L.S., for the drawings and photographs. 
