568 John Beard 



duriug the wliole year in order to preserve the contiuued existence of 

 the species. 



During the winter and spring I have examined great numbers of 

 both species . and in ali cases in which the animai was of fair size it 

 was sexually mature. If Graff's view were correct, we should expect 

 to find numerous immature individuai in the winter and spring and 

 few mature ones, whereas great numbers of mature individuals oecur. 

 I have found naturally fertilised eggs in no small quantities in the 

 middle of winter. In winter and spring one also finds young in great 

 numbers. With regard to his assertion that at Trieste he has oftenest 

 observed in autumn the sittìng of a young one on the back of an old 

 one, I can bere only remark , that Prof. Graff's so-called young ones 

 are no young ones at ali, but fully developed males; the 

 matter is dealt with fully in the next section. 



The males of 31. (jlahruìn. 



»It must have struck most naturalists as a stränge anomaly that, 

 both with animals and plants , some species of the same family and 

 even of the same genus , though agreeing closely with each other in 

 their whole Organisation are hermaphrodite and some unisexual.« — 

 Darwin, Origin of Species. Sixth edition. 1880. p. 79. 



Semper, in his paper on the genus Myzostoma J, described how he 

 once saw »ein kleines M. cirriferum , welches nur ausgebildete Zoo- 

 spermien enthielt , in der Weise auf einem großen , mit entwickelten 

 Eiern versehenen Individuum derselben Art sitzen, dass die eine männ- 

 liche Geschlechtsöflfnung ungefähr in die Nähe des Afters zu liegen 

 kam«; and adds »spätere Untersuchungen müssen diesen Punkt auf- 

 klären«. The same phenomenon had previously been seen by 0. Schmidt, 

 and curiously enough set down by him as a character of M. glahrum 

 that it possessed a knob-like process (Knopf) , on the anterior end of 

 the back. 



Semper only observed it once and then in M. cirriferum. I have 

 never observed it in that species in spite of much search , nor does 

 Prof. Graff appear to have done so either. I bave observed the phe- 

 nomenon in M. glahrum., and must say against Semper's view that 

 this so-called young one never takes up such a position that its male 



1 1. c. 



