BTUDIES ON THE ECTOPARASITIG TREMATODES OF JAPA^^ If 



The anterior sucliers 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 (Pis. T, 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 differs somewhat in 

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

 ellipsoidal, or egg-shaped (PL III, fig. 8; PI. VII, fig. 1). Its 

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

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

 tureless, membranous septum that usually runs obliquely to the long 

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

 M. reticulata. Parona and Perugia'^ mention " piccolissimi e 

 splendenti 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 veiy refractive, prismatic 

 fibres of a yellowish colour traversing its whole 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 tissue stains more or less, and in consequence, the substance of 

 the wall of the sucker appears in sections striated at right angles to its 

 surfaces. These fibres are different in appearance as well as in 

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

 like those of the posterior suckers and of the mass of connective 

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



1). Parona e Perugia — Res ligasticse, XIV. Coutribuzione per una monografia del genera 

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

 vol. X, 1890. 



