182 F, W. GAMELE, B.SC. 



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 occurence of the smaller and more numerous forms, our fauna 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 these 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. 



2. Historical Account. 



The history of British marine Turbellaria may be said to begin with 

 the publication of Dalyell's octavo volume, " Observations on some 

 Interesting Phenomena in Animal Physiology exhibited by Several 

 Species of Planarise " (1811 and 1814). Among the eight species 

 there described, is a marine one, Planaria flexilis (now known as 

 Leptoplana tremellaris), from the Firth of Forth. This animal, how- 



* Preface : " De her beskrevne nye Former ere da kun en meget liden 

 Brokdel af de ved vcae Kyster forekommende. Eu rig Host staar tilbage. 

 Man behover sandelig ikke at gaa langt for at finde en Msengde nye Arter. I 



Tangen i Fjaeren kan man jevnlig drage saadanne op hvert Kast men 



Faunsen her, navnlig for de mhidre og talrigate Arters Vorkommende, er endnu 

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

 at the end of this paper. 



