The Sexual Phases of Myzostoma. 
269 
10) The fancied analogy between the Myzostomes and Cirripedia 
addueed by Beard in bis first paper and again repeated in bis 
latest contribution, bas no vaine as proof. »Comparaison n'est pas 
raison.« If mere analogy is to be given any weigbt at ali, my view 
would certainly be the more plausible, since protandry among herm- 
aphrodite animals is far more frequent than the occurrence of com- 
plemental males (see pag. 290). 
Beard's remarks concerning the origin of hermaphroditism in 
general will be referred to in the sequel. Here enough has been said 
to show that his assertions, far from being »redolent of the trne Dar- 
winian spirita as they were to Fkitz Müller ('85), may be more 
aptly compared to an ignis fatuus. Not only bave they completely 
failed to throw any new light on the sexual conditions of the My- 
zostomes, but they bave baffled and niisled subsequent observers. 
The view which I stili maintain has at least the merit of reducing 
ali the apparently diverse sexual conditions of these peculiar para- 
sites to a single law — a more or less pronounced dichogamy. 
Simplex sigillum veritatis. 
b. The Relations of the Myzostomidae to the Chaetopod Annelids. 
The observations recorded in the first part of the present paper 
bave an important hearing on the Interpretation of some doubtful 
points in the general anatomical structure of the Myzostomes and 
hence also on the naturai affinities of the group to other Inverte- 
brata. This chapter is, therefore, in one sense a digression from 
my theme, but in another sense it may be taken as iudirect evi- 
dence in favor of the foregoing Interpretation of the sexual con- 
ditions. 
The Myzostomes bave been relegated by different authors and 
at different times to the Trematodes, Crustacea, Tardigrada or An- 
nelida Chaetopoda. Metschnikoff ('66) and Beard ('85) bave ad- 
dueed cogent reasons for placing them among the Chaetopod An- 
nelids; the former regarding them as an ectoparasitic group of 
Chaetopods, the latter with more limited definition as a family of the 
Errantia. Two of the principal authorities on the Myzostomidae, 
V, Graff and Nansen, bave never accepted this view. Von Graff 
('78 and '84 b) would unite the Myzostomidae, Linguatulidae and 
Tardigrada in a group, Stelechopoda , to be inserted between the 
Annelids and Arthropods. Nansen ('85, pag. 80) is »inclined to 
