BRITISH MARINE TURBELLARIA. 435 



2. Historical Account. 



The history of British marine Turbellaria may be said to 

 begin with the publication of DalyelFs octavo volume, "Observa- 

 tions on some Interesting Phsenomena in Animal Physiology 

 exhibited by Several Species of Plan arise " (1811 and 1814). 

 Among the eight species there described, is a marine one, 

 Planaria flexilis (now known as Leptoplana trerael- 

 laris), from the Firth of Forth. This animal, however, was 

 not new. It had been discovered and carefully described by 

 O. F. Miiller, in his ' Vermium terrestrium et fluviatilium 

 Historia,' nearly forty years before. While, therefore, Dalyell 

 made no new discovery in Planaria flexilis, his study of its 

 habits considerably increased our existing knowledge. 



The merit of his work lies in the careful and patient observa- 

 tions, the accumulation of many years, which it records. The 

 muddy haunts of the flexilis, its active behaviour when in 

 search of food, its inordinate appetite after a period of starva- 

 tion (illustrated by a case in which the bodies of three 

 individuals burst and subsequently putrefied, owing to the 

 quantity of food absorbed), the increase in bulk and changes 

 of colour due to the contained nutriment, the mode of pro- 

 pagation by eggs laid in batches like those of molluscs, and 

 the power of repairing serious injury, — all these points are 

 graphically described and extended to seven fresh-water forms. 

 In fact, this book contains even at the present time the best 

 account that we possess of the bionomics of these animals, 

 and well earned for Dalyell the dedication by v. Graff of his 

 ' Monographic der Turbellarien.' 



From 1814 to 1852 the work done on this group was confined, 

 in this country, to the description of single forms, or to the 

 records of their occurrence on our coasts. Montagu (7) 

 in 1815 discovered Planaria vittata (Prostheceraeus 

 vittatus) on the south coast of Devonshire. In 1821 

 Fleming (8) found Planaria atomata, tremellaris, and 

 vittata during a voyage round Scotland. Our knowledge of 

 this part of the British fauna was further increased by a series 



