222 ^- ^0™- 



front of the constriction which divides the middle from the posterior 

 portion of the body. 



Habitat — Gill of TJiijnnus sp. [Jap. Meljachi-maguro). 



Loca litij — Misak i . 



Drtid— August 1891. 



Although "\ve have no adequate description of Hexacotijh iliynni, 

 de Li Itoche, the only species of the genus hitherto described, I believe 

 there is scarcely any doubt that the two species here described are new. 

 Thus, in the first place, the general form of the body of both the species 

 differs from th;it of H. tliijnni as figured l)y St.-Remy '^ and Dies- 

 ing"'^; and in the second place, according to tlie statement and figure 

 of the former writer, the larger pair of hooks is situated in front of 

 the other, which is not the case in either of the species here described. 



VI. Onciiocotyli:, Diesing. 



This geiiits is clue to Diesing wlio erected it in his " Systcma helmiutlinm'' 

 (1850) for an ectoparasite found for the first time (1829) by Kuhn 3) on the gill of 

 S'jKdhis catiiliis and described by him under tlie name oi PoJi/stowK (ippcniUciiUduni. The 

 same species was afterwards redescribed more at length by Nord in a n n '), T h a e r ^)' 

 P. J. V. Benedcnß), and Taschenberg'). In 1858 T. J . v. Beneden^) 

 added a new species fO. horcalis) ; in 1878 two more new species fO. ithlircri/ito and 



1). St.-Eeuiy— Synopsis. PI. X, fig. 22. 



2). This I cite on the authority of Braun, in whose " Würmer " the figure is reproduced 

 (PI. XII, fig. 8). 



3). Kuhn — Description d'un nouveau genre de l'ordre des douves etc. Mém. d. mus. d'hist. 

 nat. T. XVIII, 1829. Also in Annal, d. seien, d'oljserv., II, 1829. Both cited on the com- 

 bined authority of Diesing, Dujardin, and Braun. 



4). Xordmann — Mikrographische Beiträge, p. 80. 



5). Thaer — De Polystomo appendiculato, 1851. Also " Ueber Polystomum appondicula- 

 tum " in Midler's Archiv f. Anat. Phys, Jahrg. 1850. The latter is cited on Braun's authority. 



6). P. J. v. Beneden — Memoire sur les vers intestinaux. 1861. p. 51. 



7). Taschenborg — Weitere Beiträge. 



8). P. J. V. Beneden — Espèce nouvelle de genre Onchocotyle vivant sur les branchies du 

 Scymnus glacialis. Bull. d. l'Acad. roy. d. Belg., t. XX, 1853. p. 59. Cited on the authority of 

 P. J. V. Beneden and Bx-auu. 



