STUDIES ON THE ECTOPARASITIC TREMATODES OF JAPAN. 1"^ 



The anterior suclccrs consist in both the genera of a pair of 

 bag-shaped bodies with thick walls, and situated one on each side 

 of the mouth-cavity (l^ls. I, II, III, & VIII). The shape of the 

 sucker is very variable according: to the different states of contraction 

 of the part of the body it belongs to, and also diifers somewhat in 

 different species ; but when in a state of rest it is generally circular, 

 ellipsoidal, or egg-shaped (PI. Ill, fig. 8; PI. YII, fig. 1). Its 

 cavity is directly continuous with that of the mouth, and in most 

 species of Microcotijle it is divided into two compartments by a struc- 

 tureless, membranous septum that usually runs obrK[uely to the long 

 axis of the body ; but tlie septum is also absent in some species, as in 

 M. reticiihila. Parona and Perugia'* mention " piccolissimi e 

 splendent! corpicciuoli rotondi disposti a gruppi, od in una fascia" on 

 the free margins of the suckers ; but I have not observed such struc- 

 tures. The wall of the sucker consists of very refractive, prismatic 

 fibres of a yellowish colour traversing its wliole thickness, which 

 remain entirely unstained in haematoxylin, picro- or borax-carmin. 

 These fibres are closely appressed to one another — the prismatic 

 shape being apparently due to mutual pressure — and only a very thin 

 layer of connective tissue is left between them. This layer of connect- 

 ive ti'^sue stains more or less, and in consequence, the substance of 

 the wall of the sucker appears in sections striated at right angles t(j its 

 surfices. These fibres are diiferent in appearance as well as in 

 colour-reaction from the muscular fibres of the body, and are perfectly 

 like tliose of the ]:)03terior suckers and of the mass of connective 

 tissue around the terminal portion of the vas deferens in the genera 



1). Parona e Perugia— Res ligustica», XIV. Contribiiziono per una monog-rafia del genere 

 Microcotyle. p. 4. Estratto dagli Annali del Museo Civico di Storia Naturale di Genova. Ser. 2, 

 vol. X, 1S90. 



