Chirocentrosus dorab is accidental and that this species of monogenetic 

 trematode nnust be considered characteristic only for Sciaenidae. 



Calicotyle affinis is encountered very often on Chimaera 



monstrosa L. (Chimaeridae, Chimaeriformes) and, although rarely, with- 

 out any doubt on Raja fullonica L. (Rajidae, Rajiformes) (Brinkmann, 

 1940, 1952a). 



Dionchus remorae is indicated only for Echeneis naucrates L. 

 (Echeneidae, Echeneiformes) and Caranx hippos L. (Carangidae, Perci- 

 formes). According to Regan, Echeneiformes could originate from forms 

 related to Carangidae (See Berg, 1940) and, thus, the finding of the same 

 species of monogenetic trematodes on representatives of these two 

 families underlies their consanguine ties, especially since the second 

 species Dionchus agassizi Goto is encountered only on Echeneidae [Remora 

 remora (L. ), R^ brachypterus L.] . During the discussion of the above- 

 mentioned (possibility, nobis) with us, L. C. Berg considered it so inter- 

 esting that he even advised us to publish a special article on the 

 subject (see further page 256 ). 



Microbothrium apiculatum has been described several times 

 and is encountered on Squalus acanthias L. (Squalidae) and in addition to 

 that is described by MacCallum (MacCallum, 1926) on Carcharhinus 

 commersonii Blanv. (Carcharhinidae). Thus, this species of monogenetic 

 trematode parasitizes representatives of two families of sharks which are 

 very distant from each other. 



Urocleidus mimus was encountered by Mueller, the author of type, 

 on Esox niger Le Sueur (Esocidae, Clupeiformes) and Lepibema 

 chrysops (Raf. ) (Serranidae, Perciformes). Subsequently this species 

 was discovered for the second time in larger quantity on the second host 

 (Mizelle and Klucka, 1953). In her resume Sproston cites Lepibema for 



some reason with a question mark, although it would have been more 

 correct to place the question mark before Esox, the finding on which is 

 undoubtedly accidental, (if it were otherwise, the finding on psox would 

 have been substantiated during the extensive research of Mizelle and 

 his co-workers) and is possibly explained by the fact that the worms came 

 to the pike from a devoured host. 



Squalonchocotyle mavori was described by Linton (Linton, 

 1940), who indicated that the worms of this species were discovered on 

 the bottom of an aquarium which contained individuals of Morone americana 

 (Gmel. ) (Serranidae, Perciformes). At the same tinne he correctly in- p. 229 



dicated doubt of the fact that these fishes could be the true hosts of the 

 given species. Sproston in her resum^(Sproston, 1946) indicates that 

 Price in his work in 1942 established a new host for S. mavori - -Sphyrna 

 zygaena (L. ) (Sphyrnidae, Selachiformes). This is absolutely untrue 



252 



