s. aoTo. 



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

 and the general form of the body to be more or less triangular. 



An interesting fact relating to the asymmetry. of the body in 

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

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

 examined for the 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, wUl be found to be of use at least as 

 a check in judging of the value of some diagnostic characters given by 

 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 ribbon. 



In Diclidophora (PI. X), the cross-section presents no great devia- 

 tion in outline from that of Microcotyle, but the general form of the body 

 is greatly modified by the fact that the four pairs of suckers are 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 (Pi. X, fig. 9), a feature 

 evidently which has suggested the generic name of Octodactyliis to 

 Sir John Dalyell. The portion which bears the suckers, the 

 " Haffcscheibe " of German authors and which I shall call the " caudal 

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

 anterior portion by a constriction of the body. In Diclid. tetrodonis 

 (PI. 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 Hexacotyle (Pi. XIII), the body is again much flattened, but 

 its absolute thickness is very much greater than in the other genera. 



