u 



S. GOTO. 



which I have mainly directed my attention in this respect, the 

 arrano-ement of the muscular fibres of the posterior sucker is somewhat 

 different from that described by Niemic.'^ The fibres may be dis- 

 tinguished into four groups. (1) The radial fibres. Tliese must again 

 be distinguished, as in Calicotyle, into two subgroups : (a) those that 

 are direct continuations of the longitudinal fibres of the body, and 

 entering the sucker, diverge irregularly in all directions, and are 

 inserted to the periphery of the sucker. They moreover cross each 

 other in the stalk of the Sucker ; those coming from the two sides 

 of the body going to the opposite sides of the sucker (PL XX, fig. 5). 

 (b) Those fibres that are confined to the radiating spokes. These start 

 from the margins of the central polygon, and running in small bundles 

 along the spokes just under the investing membrane, are inserted, 

 likewise, in the periphery of the sucker (PL XX, fig. 7, rad. mus. h.). 

 (2) The circular fibres, /. c, those that run concentrically with the 

 circumference of the sucker. This group must also be divided into 

 two sub-groups, (a) Those that belong to the ventral side. These 

 are arranged in two sets, an outer and an inner. The fibres of the 

 outer set are arranged in a single layer ; while those of the inner set 

 are uni ted into strong bundles, which are separated from one another by 

 the transverse fibres to be described presently, and fi-om the outer set 

 by an intervening layer of mesenchyma (PL XX, fig. 6, cir. mus.). 

 The circular fibres of the dorsal side are arranged in a single layer, and 

 occupy an exactly similar position to that of the outer set of the ventral 

 side. (3) The transverse fibres, i. e., those that traverse the thickness of 

 the sucker, and run therefore at right angles to its two surfaces. 

 They are, in Tr. sinuatmn, very strongly developed, and, like 



1). Nieiuic— Reoherchea morphologiques sur leg ventouses dans le ihgae animal. Kecueil 

 zoolog. Suisse. T. II, 1835. I have not been able to gain access to this paper, and am indebted 

 for its account to Braun's " Wurmer " in Bronn's " Klassen u. Ordnungen " and to MonticeUi's 

 " Saggio di una moriologia dei Trematodi." 



