282 



The matter in dispute may be very briefly stated. Idearci holds 

 that M. glabrum is dimorphic, the species being represented by herma- 

 phrodite individuals and by dwarf "complemental males". The latter 

 are "dorsicolous", i.e. they are attached to the dorsal surface of the 

 large hermaphrodite individuals which in turn adhere to the peristome 

 of Antedon rosacea. From a comparative study of several species re- 

 presenting the morphological extremes of the genus Myzostoma I con- 

 cluded that M. glahrum is monomorphic, each individual of the species 

 being from the first hermaphrodite, i.e. possessing both ovaries and 

 testes, and being like other members of the genus (notably M. cirri- 

 ferum and M. alatum) protandric, then hermaphrodite and ultimately 

 more or less hysterogynic. In other words the functional male phase 

 (Beard's "coraplemental male") passes into the functional herma- 

 phrodite phase as soon as the first ova mature, and the functional 

 female phase begins with the atrophy or disappearance of the testes*. 

 The cysticolous and entoparasitic species of the genus tend towards a 

 condition in which the functional male and female phases overlap but 

 little, thus exhibiting only a brief functional hermaphrodite phase 

 [M. eremita\ or these phases no longer overlap and thus present two 

 well-marked periods of sexual maturity, one male and the other female 

 [M. pulvinar). This I designated and still designate as "a simpler — and 

 I trust, also — a more satisfactory explanation of the sexual peculiarities 

 oi Myzostoma'''' than has been offered by Beard or any other author. 



Beard begins his paper with an attempt to reply to Friedtjof 

 Nansen, who was the first to suspect that the "complemental males" 

 were not what Beard had represented them to be^, Nansen's defence 

 need not be taken up by me. That gentleman is quite able to defend 

 himself — since events have shown that he is undaunted in the face of 

 difficulties far greater than those presented by the sexual phases of a 

 little parasite like Myzostoma. Then, too, my own defence virtually 

 includes that of Nansen, whom Beard supposes to have been re- 

 strained from going to such extremes as myself by certain "hard facts 

 of the anatomy of the complemental males". The consistency of these 

 adamantine "facts" may be tested in the course of this paper. 



In proof of the assertion that Beard has garbled my statements 

 many passages in his paper could be cited. I select the following good 

 example. Singling out one of my figures, fig. 56, he proceeds to charge 

 upon it thus (p. 308) : "From the largest of the dorsicolous forms he 



4 The female phase has not yet been seen in M. alatum, but very probably 

 occurs. 



5 Bidrag til Myzostomernes Anatomi og Histologi. Bergen, 1885. 9. pis. 

 With English resume. 



