78 Bashford Dean Me?noriaI Volume 



cm. in length) that males are about as abundant as females, and that males are by no means 

 uncommon among the larger specimens. He also found small females (30 cm. long). (2) 

 Dean contended that on general grounds it is highly improbable that Myxme is a protandric 

 hermaphrodite. He believed the evidence is not sufficient to show that Cunningham's 

 and Nansen's hermaphrodites were other than young males; he called attention to the 

 fact that, "it is not an uncommon thing to find immature eggs in the testis of a number of 

 vertebrates, Teleosts, Petromyzonts, Amphibia, where the assumption of hermaphroditism 

 to say nothing of its protandric form is entirely unwarranted." 



As an explanation of the presence of both male and female sex elements in young 

 specimens of Myxine, Dean suggested that because one side (the left) of the genital ridge 

 is usually lacking, the remaining side is precociously developed; therefore the early 

 undifferentiated condition of the sex elements, which obtains in all vertebrates to a 

 greater or lesser degree, is carried along further in the myxinoids before differentiation 

 into either ovary or testis commences. Consequently, both immature ova and testicular 

 tissue are present in the sex organ simultaneously, the former in the anterior, the latter 

 in the posterior part. He says: 



But this condition does not, I believe, imply th.it the individual is hermaphrodite, 

 except in the sense that an embryo afterwards a male may be regarded as potentially herma- 

 phrodite during a time when its genital epithelium is undifferentiated. It merely implies that 

 the hagfish is carried further along the road of developmental specialization; so that when the 

 time comes for sex-difFerentiation, the animal may become promptly female or male. 



This explanation is supported by the observations of all investigators of the generative 

 organs in myxinoids, that when both testicular and ovarian tissues are present in an 

 individual, the eggs are always very small, and may be involved m a process of degenera- 

 tion; or, as the Schreiners observed, if the eggs are good, the testicular tissue will be 

 abnormal and degenerating. Ayers alone reported finding some individuals which con- 

 tained simultaneously a testis with ripe spermatozoa and an ovary with nearly ripe eggs. 

 Dean was unable to verify Ayers' statement, nor could he agree with Ayers' view that in 

 Bdellostoma each individual is essentially bisexual. 



Conel (1917) examined twenty-four specimens of Bdellostoyna stouti which were 

 caught in Monterey Bay, at Pacific Grove, California; they consisted of one immature 

 male 33 cm. long, nme adult males, ranging in length from 36 to 42 cm., and fifteen adult 

 females varying from 34 to 40 cm. in length. No female sex elements were found in any 

 of the males, and none of the mesorchia presented the appearance of ever having con- 

 tained eggs. No testicular tissue was found in any part of the mesovarium of any female. 

 Since the adult males were larger than the adult females, it was concluded that Bdellostoma 

 stouti is not a protandric hermaphrodite. 



