TURBELLARIA 



monograph by von Graff. 1 A similarly comprehensive and indis- 

 pensable treatise by Lang, on the Polycladida, 2 contains references 

 to all previous publications on the group, among which the 

 papers by Quatrefages, Johannes Miiller, Keferstein, Minot, and 

 Hallez stand out conspicuously. Moseley's work 3 on the Land 

 Planarians of Ceylon is undoubtedly the most revolutionary 

 paper referring to this group, and the 

 best contribution towards elucidating 

 the structure of the Tricladida at a 

 time when the subject was very obscure. 

 A monograph on Land Planarians is 

 being prepared by von Graff. 



The Turbellaria are divided into: 

 (1) Polycladida, marine forms with 

 multiple intestinal branches ; (2) Tri- 

 cladida, marine, fresh-water, and ter- 

 restrial Planarians with three main 

 intestinal branches ; (3) the Rhabdocoe- 

 lida, as varied in habit as the Triclads, 

 but possessing a straight and simple or 

 slightly lobed, intestine. A detailed 

 description of an example of the Poly- 

 clads, and then a comparative account 

 of each division, will now be given. 



Turbellaria. I. Polycladida. 



Description of Leptoplana tremellaris. 



Appearance and Habits. An ac- 



count of the Polyclad Turbellaria may 

 be fitly prefaced by a description of 

 a very common representative, Lepto- 

 plana tremellaris, so called on account 

 of the thin, flat body which executes 

 when disturbed, quivering or tremulous swimming movements. 



sends branches to the margin 



1892. 



Monographic d. Turbellarien. I. Rhabdocoelida, 1882. Die Acoela, Leipzig, 



2 "Die Polycladen," Fauna u. Flora d. Golfes v. Neapel, Monogr. XI. 1884. 



3 Phil. Trans. 1874, p. 105. 



