The Sexual Phases of Myzostoma. 
269 
10) The fancied analogy between the Myzostomes and Cirripedia 
adduced by Beard in bis first paper and again repeated in bis 
latest contribution, bas no value as proof. »Comparaison n’est pas 
raison.« If mere analogy is to be given any weight at all, my view 
wnuld certainly be tbe more plausible, since protandry among herm- 
aphrodite animals is far more frequent than tbe occurrence of com- 
plemental males (see pag. 290). 
Beard’s remarks concerning the origin of hermapbroditism in 
general will be referred to in tbe sequel. Here enough bas been said 
to sbow tbat bis assertions, far from being »redolent of the true Dar- 
winian spirit« as tbey were to Fritz Müller ('85), may be more 
aptly compared to an ignis fatuus. Not only bave tbey completely 
failed to throw any new light on tbe sexual conditions of the My- 
zostomes, but tbey bave baffied and misled subsequent observers. 
The view wbicb I still maintain bas at least tbe merit of reducing 
all tbe apparently diverse sexual conditions of tbese peculiar para- 
sites to a single law — a more or less pronounced dicbqgamy. 
Simplex sigillum veritatis. 
b. The Relations of the Myzostomidae to the Chaetopod Annelids. 
Tbe observations recorded in tbe first part of tbe present paper 
bave an important bearing on tbe interpretation of some doubtful 
points in tbe general anatomical structure of tbe Myzostomes and 
hence also on tbe natural affinities of tbe group to otber Inverte- 
brata. Tbis chapter is, therefore, in one sense a digression from 
my tbeme, but in another sense it may be taken as indirect evi- 
dence in favor of tbe foregoing interpretation of tbe sexual con- 
ditions. 
Tbe Myzostomes bave been relegated by different authors and 
at different times to tbe Trematodes, Crustacea, Tardigrada or An- 
nelida Chaetopoda. Metschnikoff ('66) and Beard ('85) bave ad- 
duced cogent reasons for placing them among tbe Chaetopod An- 
nelids; tbe former regarding them as an ectoparasitic group of 
Cbaetopods, the latter with more limited definition as a family of the 
Errantia. Two of the principal autborities on the Myzostomidae, 
V. Graff and Nansen, bave never accepted tbis view. Von Graff 
('78 and '84 b) would unite tbe Myzostomidae, Linguatulidae and 
Tardigrada in a group, Stelechopoda , to be inserted between tbe 
Annelids and Arthropods. Nansen ('85, pag. 80) is »inclined to 
