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Part III. — Ttventy-sixth Annual Report 



were still alive when observed, and appeared to be endeavouring to leave 

 the fish, and making their exit by the mouth. In this species the head is 

 comparatively small and compressed and provided with two nearly circular 

 suckers placed opposite each other on the flattened sides, as shown in the 

 drawing (Plate V\, fig 5). Each of the suckers measure about 5 mm. in 

 diameter, and they are surmounted by a slightly projecting ledge armed 

 on the under side with numerous minute hook-like denticles. 



One incomplete specimen measured about 26 inches in length, and 

 another about half that length, (PI. VI., fig. 2). According to Diesing, 

 this Cestode may attain a length of six feet. It has been recorded by 

 Rudolphi from Orthagoriscus mola, captured in the Mediterranean. 

 Prof. Linton also records this species, and mentions one of the specimens 

 as being 150 centimetres long (nearly sixty inches). Van Beneden 

 records the same worm from the coast of Belgium, and states that he 

 has seen a score of individuals in a single fish,* while Malard also 

 records it from the coast of La Manche, and apparently all from the 

 same species of Sunfish. 



Genus Schistocephcdus, Creplin (1829). 



Schistocephalus solidus (0. F. Miiller). PI. VII., figs. 7-8. 



1776. Tcenia solida, O. F. Miiller, Zool. Danicse Prodromus, 

 pp. 26-37. 



1808. Bothriocephalus solidus, Rud., Entozoorum, Hist. Nat., 

 p. 54. 



1829. Schistocephalus dimorphus, Crep., Nov. obs. de Entoz., 

 p. 95. 



1850. Schistocephalus dimorphus, Dies., Syst. Helminth., 

 vol. i., p. 584. 



1893. Schistocephalus dimorphus, Olsson, Bidrag till Skand 



Helminth fauna, ii., p. 15. 

 1896. Schistocephalus solidus, F. W. Gamble, in the Camb. 



Nat. Hist., vol. ii., p. 84. 



The three-spined Stickleback, Gasterosteus acideatus, is a little fish not 

 uncommon in the Loch of Loirston, near the village of Cove, Kincardine- 

 shire. On visiting this loch towards the end of May 1901, my colleague, 

 Dr. H. C. Williamson, found a large proportion of the Sticklebacks infested 

 with worms, so much so that many of the little fishes had their abdomens 

 distended with the parasites, causing them to assume an abnormal appear- 

 ance. Many of the fishes examined had the entire abdominal cavity 

 occupied by the parasites. In some cases there was only a single worm of 

 large size, folded upon itself two or three times, and which, when 

 straightened out, was much longer than the fish. In other cases two, and 

 sometimes several, specimens were present, but these were generally of 

 smaller size. 



The loch is frequented by a number of w T ater-birds such as Sea-gulls 

 and Terns, and the Heron is also occasionally observed about the loch. 

 These birds are liable to be infested with the tape- worm, Schistocephalus 

 solidus, Rudolphi, in its sexually-mature stage, and the Stickleback 

 parasite mentioned above is the same worm in its sexually-immature 

 condition. 



It is thus evident that some of the birds frequenting the loch had been 

 giving shelter to the Schistocephalus, and that larvse hatched from the 



* Les Poissons des cotes de Belgique, 87. 



