CHAPTER V 



NEMERTINEA 



INTRODUCTORY EXTERNAL CHARACTERS ANATOMY CLASSIFICA- 

 TION DEVELOPMENT HABITS REGENERATION BREEDING 



GEOGRAPHICAL DISTRIBUTION -LAND, FRESH-WATER, AND 



PARASITIC FORMS AFFINITIES 



The Nemertinea form a compact group, the affinities of which 

 have not been at present clearly determined. Several species 

 were mentioned and described in the works of various naturalists 

 during the latter half of the eighteenth century, though their 

 anatomy was not understood until considerably later. The first 

 mention of any member of the group was made by the Eev. W. 

 Borlase in his Natural History of Cornwall, published in 1758. 

 He gives a short description and a rough figure of Lineus 

 marinus. From that time the increase in the knowledge of the 

 group was very gradual. New species were from time to time 

 described, but few of the descriptions could boast of much com- 

 pleteness, and many erroneous views were held until compara- 

 tively recent years. The group was very variously classified, but 

 the general arrangement in early times seems to have been to 

 unite it with the Planarians. Valuable contributions to the 

 history of the development were made in 1848 and the few 

 subsequent years by Desor, 1 Gegenbaur, 2 Krohn, 3 and Leuckart 

 and Pagenstecher 4 ; and more recently by Metschnikoff 5 and 

 Salensky. 6 



1 P. Boston Soc. vol. vi. 1848. 



2 Zeitschr. wiss. Zool. Bd. v. 1854, p. 344. 



3 Arch. Anat. 1858, p. 289. 4 Ibid. 1858, p. 558. 



5 Mem. Ac. St. Pctersb. ser. vii. torn. xiv. 1869. 



6 Zeitschr. wiss. Zool. Bd. xliii. 1886, p. 481. 



