28 s. GOTO. 



direct continuation of the investing membrane of the body. 



The pair of suckers above described has been mistaken hj Tas- 

 chenberg^-* for the terminal vesicles of the excretory system (see p. 5). 



Calicotyle — Anterior sucker — In this genus the anterior sucker is 

 developed far more imperfectly than in th<:)se hitherto described, and 

 is also totally different from them in structure. It is constituted by 

 a deep invaginati(3n of the ventral side of the body just behind the 

 mouth (PL XIX, fig. 8). From the inner surface of the investing 

 membrane that lines the cavity of the sucker, numerous muscular 

 fibres take their origin, and diverging in vari(jus directions, become 

 continuous with the longitudin-d fibres of the body. Besides these, 

 circular fibres are exceptionally developed in this part. Owing to this 

 local development of the musculature, the anterior sucker seems in a 

 surface view to be pretty well defined from the surrounding mes- 

 enchyma, and to form a distinct organ (LM. XIX, figs. 1 and 4) ; but 

 sections show that tliis is l)y no means the case. Morphologically 

 speaking, it would be more correct, therefore, to call it a rudimentary 

 sucker (pse udo ven tose) . 



Posterior sucker — This is situated on the ventral side at the [)0s- 

 terior extremity of tlie body. Its ventral surface is marked out into 

 a central heptagonal and seven periphend areas Ijy elevations of the 

 ventral surface radiating from the wall of the central ]iolyg(^n. This 

 central polygon does not occupy exactly the middle of the sucker, but 

 is situated a- little more anteriorly. The hindmost area which is 

 the largest, occupies the median line of the body, while the others are 

 arranged symmetrically on either side, and decrease in size from 

 behind forwards (1*1. XIX, figs. 1 and o). 



The nuisculature of the sucker consists of three sets of 

 fibres, Avhich may be called the radial, the transverse or dorso-r entrai, 



1). Taschenberg — Weitere Beiträge, p. 13. 



