STUDIES ON THE ECTOPARA.SITIC TREMATODES OF JAPAN. 185 



asymmetry presents itself in some internal organs, as in tlie different lengths of the 

 two branches of the intestine. (2) In all the species of Miorocotyle what Lorenz 

 calls "Penis" is distinctly present ') as also the genital cloaca; and his observa- 

 tion as to the separate opening' of the male and female duets is, as P a r o n a and 

 Perugia have pointed out, erroneous. (3) In the species of Axim which I have 

 studied, and which are described below, the vagina is situated, as in Microeotyle, oji the 

 dorsal median line. (4) I have observed some specimens of Axine heteroceica dis- 

 charge, while kept in sea-water in a watch-glass, a large number of eggs from the 

 uterus, which was afterwards found to be much enlarged in consequence. (6) In all 

 the three species of Axine I have studied, two series of suckers are distinctly present, 

 although one of the series is much reduced in number. Thus we find no absolute 

 difference between the two genera, the difference lying only in the degree in which 

 the asymmetry is manifested in each. Still the general form of the two genera 

 presents quite a perceptible difference, so that we may keep them distinct for con- 

 venience' sake. A sharp distinction between two such nearly allied genera can not 

 be expected. 



In view of the facts above summarised, the diagnoses given by the preceding 

 writers are no longer quite satisfactory ; I therefore venture to modify them as 

 follows : 



Body elongated, mostly symmetrical, with the an- 

 terior end rounded and the posterior end usually pointed. 

 With a pair of suckers in the mouth-cavity. The caudal 

 disc, which is in most species separated from the hody 

 proper by lateral constrictions, usually bears a large 

 number of minute suckers. Genital cloaca present ; 

 genital opening on the ventral median line ; vaginal 

 opening single, situated in the median line on the dorsal 

 side, 1^0 chitinous hooks at the posterior .end of the 

 body. 



1). Cf. Parona and Perugia — Res ligustioae, XIV. p. 8. 



