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Part III. — Twenty -third Annual Report 



parallel sides, springs from the rounded end ; this process is armed at the 

 extremity with four hooked teeth, the two outer teeth are large and 

 strong, with an expanded base, but the other two are smaller and more 

 slender (fig. 20). 



According to the authors of the Recherches, this species when extended 

 measures about 5 mm., but in the specimen represented by the drawing 

 (pi. vi., fig. 19, of this paper), the body is considerably contracted in 

 length, and is consequently wider, the peduncle at the posterior end, 

 which when fully extended is very slender and narrow, is also shortened 

 in the specimen figured. This peduncle is very fragile, and is therefore 

 occasionally incomplete, and for that reason, and also because it can be 

 folded back under the body of the animal, it may at times easily escape 

 being noticed, 



Genus Plectanocotyle, Diesing. 



Plectanocotyle Lorenzii, Monticelli. 



1899. Plectanocotyle Lorenzii, Monticelli, Di una nova Specie del 

 genre Plectanocotyle; Atti. K. Acad, delli Sci. di Torino, 

 vol. xxxiv., p. 1, pi. 1 (separate copy). 



1901. Pliyllocotyle gurnardi, T. Scott, 19th F.B. Kept., Pt. III., 

 p. 147, pi. viii , fig. 23. 



A Trematode recorded by me under the name of Pliyllocotyle gurnardi 

 in the Nineteeth Annual Report of the Fishery Board for Scotland 

 (1901), was afterwards recognised as belonging to a species described by 

 Dr. F R. Sav. Monticelli two years previously under the name mentioned 

 above. 



This Plectanocotyle had been obtained by Dr. Lorenz some years before 

 on a species of Gurnard, Trigla sp. The slender posterior peduncle, so 

 characteristic of Pliyllocotyle gurnardi, is apparently absent in Plectano- 

 cotyle. The Scottish specimens from Trigla gurnardus were examined 

 by Dr. F. R. Sav. Monticelli, and recognised by him as belonging to the 

 species he had described in 1899. 



As already pointed out, the peduncle in Pliyllocotyle, being so slender 

 and fragile, is easily damaged, and when it gets torn off or folded under 

 the body, and when the body is shortened by contraction — a contingency 

 not uncommon when fishes infested by the parasites are preserved in 

 spirit or formaldehyde — the one Trematode may easily be mistaken 

 for the other. 



Genus Microcotyle, van Beneden and Hesse (1863). 



Microcotyle donavani, van Beneden and Hesse. PI. vi., fig. 21. 



1863. Microcotyle donavani, v. Ben. and Hesse, Recherches, 

 p. 114, pi. xii., figs. 1-11. 



This species was found on the gills of a Ballan Wrasse (Labrus 

 bergylta, Ascan.), obtained by Dr. H. C. Williamson in the Moray Firth 

 on October 23, 1904, and also on a Ballan Wrasse captured in the 

 North Sea by Mr. Bowman. 



The species is narrow and elongated, and at the posterior end there is 

 a row of small suckers along each margin ; the number of suckers in each 

 row appears to vary to a small extent. In the specimen represented by 

 the drawing (fig. 21) the number in each row is about thirty-four. 



Microcotyle donavani does not appear to be a rare form ; the authors 

 of the Recherches state that it has been found in abundance on the 



