434 F. W. GAMBLE. 



anatomy, few naturalists in this countn^ have devoted much 

 attention to them. When once a keen interest, however, is 

 aroused, the number of new and morphologically important 

 forms that may be found in a limited area is beyond antici- 

 pation. This has been well expressed by Jensen in the preface 

 to his work on the Turbellaria of the west coast of Norway : 

 " The new forms described here are only a very small part of 

 those that occur on our coasts. A rich harvest remains behind. 

 Indeed, one has no need to go far to find numbers of new 

 species. Among seaweed they are frequently brought up at 

 every haul. At greater depths, again, other new species are 

 found ; but as regards the occurrence of the smaller and more 

 numerous formsj our fauua is still quite unknown."^ 



This quotation applies very appositely to the present case. 

 As yet only a small portion of our coast has been explored. 

 Extended observations are urgently needed. Still, from my 

 own list, together with the records of other naturalists who 

 have from time to time noted the occurrence of British forms, 

 it appears that our fauna already includes fourteen Polyclads, 

 two Triclads, and fifty-five Rhabdocoeles — a total of over 

 seventy species. It is to the description of these that I address 

 myself. In doing so I shall try to indicate the distinctive 

 points, structural and bionomical, that separate the various 

 forms, reserving a more detailed account of the anatomy of 

 new or partially known species to a future paper. 



The specific descriptions (which largely confirm those of 

 previous observers) are taken, except where otherwise stated, 

 from my own observations. 



One section of the group — the parasitic Turbellaria — is 

 omitted. These forms undoubtedly occur on our coasts, but I 

 have had no opportunity for their investigation. 



1 Preface : " De her beskrevne nje Former ere da kun en meget liden 

 Brokdel at' de ved vore Kyster lorekoumieude. Eu rig llost staar tilbage. 

 Man behover sandelig ikke at gaa laugt for at fiude en Msengde nje Arter. I 

 Tangen i Fjaereu kan man jevnlig drage saadaune op hvert Kast .... men 

 Faunsen her, navnligfor de mindre og talrigste Arters Vorkommende, erendnu 

 belt unbekjendt " (49). The numbers in brackets refer to the list of literature 

 at the end of this paper. 



