20 s. GOTO, 



while that of the other was only 0.095 mm. On the longer side the 

 largest suckers are, as in Microcotijle, generally found in the middle 

 portion ; but on the shorter side the suckers gradually diminish in 

 size from before backwards. In A. aherraus, however, the suckers are 

 all of nearly equal size on the longer side. Lorenz'^ and others 

 mention the suckers only on the longer side ; but in all the species 

 studied by me they are present on both sides (PI. ^^I^, figs. 1, 5, 

 & 7). 



Xow as to structure, each posterior sucker may be likened to a 

 flattened, rectangular bag open on the ventral side, the broader sides of 

 which face forwards and backwards and have a very thick wall, while 

 on the narrower sides the wall is very thin. This bag is supported 

 by a chitinous'^ frame consisting of five pieces, viz., four lateral pieces 

 in pairs and one median. Of the four lateral pieces two are imbedded 

 in the substance of the anterior wall and two in that of the posterior 

 wall, both along the lateral margins (PI. II, fig. 7). These are 

 curved like a hook, are somewhat triangular in cross-section, and are 

 entirely solid. The rods of the anterior wall (a) are, at the bottom of 

 the sucker, directly continued on into the posterior wall (n'y^; and the 

 whole has, therefore, somewhat the form of a hook (cf. V\. Ill, fig. 1 

 & PI. II, ûg. 7). Those of the posterior wall (h) end bluntly at the 



1). Lorenz — Ueber die Organisation der Gattungen Axine und Microcotyle. Wiener 

 Arbeiten von Claus. Bd. I, Hft. 3, 1878. p. 4. 



2;. I have used the word " chitinous " here and shall use it in describing the hooks in 

 accordance with the usual custom ; but it should be noted that these pieces are souietiuies 

 well stained with haematoxylin — exactly under what circumstances I have not been able to 

 make out ; but one condition seems to be that the specimen be preserved after a certain dis- 

 integration of the tissues has set in— and that the hooks are soluble in a solution (35 7o) of 

 caustic potash. 



3). I take this opportunity to correct my statement on this head with regard to Diplozooii 

 NipjJOiiiciun. In my paper on this worm (I.e.) I have described the piece imbedded in the 

 posterior wall and projecting towards the median piece as the process of the paired (lateral) 

 piece of the posterior wall, whereas it is in reality the direct continuation of the paired piece of 

 the anterior wall, just as in Mkrocotijlc. 



