BY W. A. HASWELL. 49 



anterior. It will be iiecessar}-, therefore, to decide which of 

 these opposed views is to be adhered to in making this comparison. 



Spencer's contribution to the subject was published at least a 

 3^ear before Lonnberg's; but the latter reached his conclusion 

 independently, and adduces several reasons of some weight in 

 support of his position. He alleges, in the first jDlace, that the 

 animal creeps in the direction of the end which bears the funnel. 

 On this point I am unable to make any statement, as I have not 

 had an opportunity of observing living specimens. But, in the 

 absence of other evidence, it is worthy of note that Wagener 

 states "Die Schwanzkrause bleibt meist ruhig wahrend der Kopf- 

 theil des Thieres sich langsam bewegt." 



The direction of the spinules on the surface Lunnberg regards 

 as affording further evidence in favour of his view. If the end 

 with the funnel is posterior, then these spinules lie with their 

 points directed forwards. Further support Lonnberg conceives 

 to be derivable from the structure of the nervous system, nerve- 

 cells being more numerous in the commissure at the end which 

 he looks upon as anterior. Monticelli (5), however, states that the 

 contrar}^ is the case. 



But a comparison of the reproductive apparatus of Gyrocotyle 

 with that of allied forms appears to me to place it beyond a doubt 

 that the sucker end is that which corresponds to the end usually 

 regarded as anterior. If we take the contrary view it is 

 impossible to trace any correspondence in the arrangement of the 

 parts : whereas a general unity of plan at once becomes apparent 

 on the position becoming reversed. When we bear in mind that, 

 though Gyrocotoyle is unsegmented, it possesses a number of 

 highly specialised Cestode features in its adult structure, and is 

 characterised, moreover, by the occurrence in its life-history of 

 the peculiar and characteristically Cestode hexacanth larva, the 

 necessity for tracing such a correspondence becomes manifest. 

 The end which bears the sucker is seen, as a result of such a 



* Whether or not this cori-esponcis to the anterior end in other classes of 

 Flat-worms is a question outside the limited scope of the present paper. 

 4 



