s. GOTO. 



of the body, the posterior end has come to be situated quite laterally, 

 and the general form of the l^ody to be more or less triangular. 



An interesting fact relating to the asymmetry of the body in 

 Axinc is that the longer side may be either the left or the right. 

 Thus, in A. hetcrocerca, out of the nine specimens which I have 

 examined for tlie purpose, three had the left side of the body shorter 

 while in the remaining six the right side was shorter. This fact, 

 though apparently insignificant, will be found to be of use at least as 

 a check in judging of the value of some diagnostic characters given b}^ 

 previous workers. 



The cross-section of the body is in Axine band-shaped ; and the 

 thickness of the body diminishes, while its breadth increases, as we 

 proceed towards the posterior part, so that in this region the cross- 

 section presents the shape of a narrow riljbon. 



In DiclidophoM (Pi. X), the cross-section presents no great devia- 

 tion in outline from that of Microcotijlc, but the general form of the ÎDody 

 is greatly modified by the fact that the four pairs of suckers arc hemi- 

 spherical, and are borne on the posterior margin of the body arranged 

 in a semicircle or in a horse-shoe shape. Moreover, in many species 

 each sucker is borne on a long pedicel (PL X, fig. 9), a feature 

 evidently which has suggested the generic name of OdOilactijlus to 

 Sir John Dal yell. The portion which bears the suckers, the 

 " Haftscheibe" of German authors and which I shall call the " caudjil 

 disc," is in all species more or less distinctly; separated from the 

 anterior portion Ijy a constriction of the body. In DidlcL IdrodoniH 

 (PL X, figs. 1 & 2), however, the posterior portion of the body is con- 

 siderably elongated, so that the transition to the caudal disc is more 

 gradual. 



In Hexacolijle (PL XIII), the body is again much flattened, but 

 its absolute thickness is verv much greater than in tlie other genera. 



