117 Part III. — Twenty -third Annual Report 



same species of Labrus in the month of March. Several specimens were 

 found on the gills of the Labrus from the Moray Firth and from the 

 North Sea, but none were very perfect. This species of Microcotyle is 

 not only very slender, but is also without consistence, and therefore 

 easily injured. The length of the specimen represented by the drawing 

 is 5*3 mm. Figure 22 is a front view of one of the suckers seen under 

 a moderately high magnification. 



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



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

 p. 112, pl. xii., figs. 12-18. 



This species has a general resemblance to M. donavani, but differs in 

 possessing about double the number of suckers at the posterior end 

 (fig. 21). The structure of the cesophagian bulb also differs in the two 

 species. 



The length of the specimen represented by the drawing is about 7mm. 



Habitat. — On the gills of the Bass, Labrax lupus. I am indebted to 

 my son for specimens of this species. 



Fam. Gyrodactylid^:. 



Genus Diplectanum, Diesing (1858). 



Diplectanum wquans] Diesing. PI. vi., fig. 24. 



1858. Diplectanum aquans, Diesing, Revis. derMyzhelm., p. 77. 



1863. Diplectanum cequans, v. Ben. and Hesse, Recherches, 

 p. 122, pl. xiii., figs. 9-22. 



This Trematode is common on the gills of the Bass, Labrax lupus, but 

 being very small it is easily missed. The length of the specimen repre- 

 sented by the drawing (fig. 24) is about 2mm. 



In Diplectanam c&quans the head is armed with two moderately strong 

 hooked spines on each side of a deeply concave cleft ; this cleft is occupied 

 by a process thickly covered with minute prickles, as shown in the 

 drawing. 



I am indebted to my son for this small but interesting species. 



The following is a list of species belonging to the Trematoda that have 

 been described or recorded, and for the most part figured, in Part III. of 

 the Annual Reports of the Fishery Board for Scotland. The species now 

 recorded are included in the list. The names are arranged in alphabetical 

 order. 



Name of the Species. 



Annual Report where published, 



and Number of Plate where 



figured. 



Acanthocotyle monticellii, T. Scott, 

 Anthocotyle merluccii, v. Ben. and Hesse, 

 Callocotyle kroyeri, Diesing, 

 Dactycotyle pollachii, v. Ben. and Hesse, 

 Diplectanum aequans, Diesing, - 

 Epidella hippoglossi, 0. F. Miiller, 

 Heterocotyle pastinacce, T. Scott, - 



20th Report; Pl. xiii.; 1902. 

 19th „ Pl. viii. j 1901. 



Present Report ; Pl. vi. 

 19th Report; no figure. 

 22nd „ Pl. xvii.; 1904. 



