THE DERIVATION OF THE FRESHWATER AND 



LAND NEMERTEANS, AND ALLIED 



QUESTIONS. 



THOS. H. MONTGOMERY, Jr., Ph.D. 



In a recent paper de Guerne ^ has given a discussion of the 

 origin of the freshwater nemerteans, which, however, is but a 

 brief collaboration of the facts of previous writers ; so that I 

 am led to a further consideration of the same problem, and to 

 a more detailed discussion of some of the interesting questions 

 in connection with it. 



I have previously attempted a revision ^ of the freshwater 

 nemerteans, — of those at least which have been sufficiently 

 diagnosed, according to which we have four well-defined 

 species belonging to the genera Monopora, SticJiostemnia, and 

 Neme7'tesQ) ^ Freshwater forms have been found in Europe, 

 in England, France, Germany, Russia, Switzerland, Austria, 

 and Italy ; in Turkestan, at Taschkend ; in Africa, Kingani 

 River ; and in North and Central America. Five species of 

 land nemerteans have been described, four belonging to the 

 genus Geonemertes and one to Tetrastemma ; the latter was dis- 

 covered in the Bermudas, the Geonemertes species respectively 

 in the Pelew Islands, Australia, New Zealand, and Frankfurt 

 (Germany).* 



Now when the land and freshwater faunas have been more 

 thoroughly investigated, — for at the present time they are 

 known much less completely than the marine faunas, it is safe 

 to predict that land and freshwater nemerteans will be found 



1 Ann. and Mag. of Nat. Hist., X, 1S92. 



2 Zeitschr. f. wiss. ZooL, LIX, i, 1895. 



3 It is not yet determined whether Nemertes polyhopla, Schmarda, is a true 

 Neinertes. 



* Geo7iejnertes chalicophora, Graff, was found among exotic plants in the Frank- 

 furt botanical gardens and so is probably not indisjenous there. The description 

 of Geonemertes Novae-Zelandiae, Dendy, appeared in Annals and Mag. of N'at. 

 Hist., December, 1894, after my previous paper had been put in print. 



