Genital System of the tAyxinoidea 69 



The data which Doctor Dean accumulated indicate that he was especially interested 

 in the questions of hermaphroditism, time of spawning, and the descent and relationships 

 of the Myxinoidea. These subjects in particular will be discussed; in each case the 

 literature will be reviewed briefly m order to summarise for the reader the results of 

 previous investigations, thereby enabling him to orient himself in the subject under 

 consideration. 



HERMAPHRODITISM IN THE MYXINOIDEA 



Because the myxinoids have been so little understood, they have been more mis' 

 represented and maligned than any other vertebrates. The earliest investigators classi' 

 fied them with the worms. Even after this error had been corrected, and the slime eels 

 accorded a place with the vertebrates, complete enjoyment of their new position 

 was denied them on account of their round, leech-like mouths, indicated by the word 

 "Bdellostoma." The shape of the mouth coupled with the fact that the eels were often 

 brought to the surface of the water with their heads, and even their entire bodies, buried 

 in the flesh of fish caught on hooks or in traps, misled many investigators to believe that 

 the myxinoids are parasites, and therefore are degenerate. I am convinced, however, that 

 the myxinoids are not parasites. They do not attack free-living fishes, but only fishes 

 caught on hooks just as other predatory fishes do. The eel feeds by rasping into tlie 

 flesh of the large hooked fish and may bore its way into the body of this fish and eat 

 everything but the skin and the bones, being found inside the remains of its prey when 

 this is brought to the surface. Many students of the myxinoids have found that the 

 eel does this to fishes on lines set over night or even left for a few hours where these eels 

 are plentiful. However, the eel was not Uving as a parasite either on the outside or in the 

 inside of its prey before this was hooked. 



In spite of the fact that many observers have proved that the myxinoids are free- 

 living bottom feeders and not parasites in any sense of the word, some authors continue 

 to stigmatize them as being the only parasites among the vertebrates. Hence many 

 writers are still discussing the pros and cons of this form of degeneracy in these lowest 

 vertebrates. Furthermore another charge filed against the Myxinoidea of conduct unbe- 

 coming vertebrates is the alleged practice of the lowly method of reproduction — herma- 

 phroditism. The origin and development of this idea in the minds of certain investigators 

 can best be presented by giving a resum ' of the literatqre. 



REVIEW OF THE LITERATURE 



The earliest recorded discussion of the structure of the reproductive organs in the 

 myxinoid fishes was written by Johannes Miiller in 1843. He briefly described the male 

 and female genital systems in IVlyxine glutinosa and Bdellostoma forsteri, giving an account 

 of the structure of the testis and ovary. 



