Manchester Meviot'rs, Vol. xlv. {igoi), No. \4- 15 



The similarity in general structure between the 

 northern and southern specimens of Gomada,z.nd especially 

 the remarkable resemblance in detail of the parapodia, 

 proves that they had a common origin. The absence of 

 a species showing the same details in the tropics makes it 

 difficult to believe that a migration is taking place or can 

 have taken place since the restriction of the tropical belt, 

 either from north to south or from south to north. 



As the genus Goniada has not been taken in the deep 

 sea, we have no evidence that a passage has been made 

 through the tropics by this means. 



The evidence, with regard to the distribution of this 

 genus, therefore, supports the Bipolar Theory for littoral 

 temperate waters. 



(ii.) Arenicola daparedii. 



Distribution: Naples, California (Crescent City, 41° 

 44' N. lat., marks its northern limit), Straits of Magellan (?). 

 New to the Falkland Islands. The genus is cosmopolitan 

 in shallow waters. 



The distribution of this shore-dwelling form is 

 interesting. Its occurrence on the Californian coast and 

 at the Falkland Islands seems to support Ortmann's view 

 that the existence of a passage of cool water along the 

 western shores of America enables an interchange of 

 northern and southern temperate forms to take place, but, 

 as this form has not \'et been taken in an intermediate 

 locality, we have no proof of its transmission. Its 

 occurrence at the Falkland Islands and in the 

 Mediterranean cannot be explained by Ortmann's view 

 that a similar interchange of forms takes place along the 

 western shores of Africa, for it has not been taken on the 

 west African shores. 



It is worthy of note that this species in the adult 

 stage is a burrowing shore-dwelling form, therefore its 



