A discussion of certain questions of nomenclature, as applied to parasites. 197 



In 1845, DujARDiN proposed under Distoma the subgenus Brachy- 

 coeliuni with the following diagnosis: 



"Intestin divisö en deux branches courtes, renfl6es en massue, et 

 pr6c6d6 d'un long oesophage filiforme." 



No type species was designated, but the following species were 

 placed in Brachycoelium. 



1. J). TieteroporumTivs., 1845. [Examined by Dujardin; type of Pj/cno- 



porus by Looss, 1899; probably a Lecithodendrium — Looss, 1896; 

 to Lecithodendrium by Stossich, 1899, p. 9.] 



2. D. arrectum Duj., 1845. [Examined by Dujabdin; to D. (Dicro- 



coelium) by Stossich, 1895; admitted by Luhe, 1899, p. 536, to 

 be a species inquirenda, yet selected by him as type for 

 Brachycoelium; admitted by Looss, 1899, p. 614, to be a species 

 inquirenda.] 



3. "JD. clavigerum Rud.", of Duj., 1845. [Examined by Dujardin ; ad- 



mitted by Looss, 1894, p. 101, to be a misdetermination and re- 

 named D. confusum, the latter taken as type of Prosotocus by 

 Looss, 1899, p. 616. 



4. D. aassicolle Rud., 1809. [= Fase, salamandrae Feölich, 1789, 



renamed; examined by Dujardin; erroneously placed in B. {Dicro- 

 coelium) by Stossich, 1889 ; retained bere by Parona, 1896, pp. 13 

 — 16; returned to Brachycoelium by Stossich, 1897, p. 9; desig- 

 nated type of Brachycoelium hj StijuEs and Hassall, 1898, p. 83; 

 placed in Lecithodendrium by Stossich, 1899, p. 9, and by Luhe, 

 1899, p. 356.] 



5. D. retusum Duj., 1845. [Examined by Dujardin; to D. (Dicro- 



coelium) by — ? — ; admitted by Looss, 1899, p. 614, to be prob- 

 lematic] 



Here we have a subgenus, containing five species, united by a 

 perfectly clear diagnosis, and from Dujardin's point of view and from 

 the point of view of his time, forming a more or less natural group. 

 The subgenus is defined fully as clearly as Dicrocoelium, Äpoblema, 

 Echinostoma, Crossodera, and thousands of other genera and subgenera 

 of its time. It does not appear to be preoccupied or antedated. No 

 grounds are apparent which would justify an author in ignoring it 

 when studying any of the five forms mentioned, or when studying other 

 forms which would fall under the same diagnosis. Natural or unnatural, 

 from the Standpoint of the present day, it must be admitted as en- 

 titled to recognition; and if any author later than Dujardin, 1845, 

 desires to propose another genus for any one of the five species 

 mentioned, or for any other distomes which correspond to the diagnosis 

 given by Dujardin, it is incumbent upon the proposer to show wherein 



