[Reprinted from THE AMERICAN NATURALIST, Vol. LI., December, 1917.] 



NOTE ON THE HABITAT OF GEONEMERTES 



AGRICOLA 1 



THE terrestrial nemerteans include a small number of species, 

 all belonging, apparently, to one genus, but widely scattered 

 over the world. They occur conspicuously on islands, some of 

 which are well removed from any large mainland. The origin 

 of these land nemerteans is a matter of some interest, and sev- 

 eral suggestions have been made relative to the manner of their 

 evolution. One of these terrestrial nemerteans, Geonemertes 

 agricola (W.-S.), was found at Bermuda by v. Willemoes-Suhm 

 (1874). The anatomy of this species was subsequently de- 

 scribed in detail by Coe (1904), who gave some attention, also, 

 to the habits of the worm. These observers, as well as Verrill 

 (1902), agree that G. agricola is to be found "only along the 

 shores of mangrove swamps and on the adjacent hillsides" (Coe, 

 p. 566). Coe found it "not only above high- water mark but 

 also for some distance along a zone which is covered for a short 

 time each day with sea water," but noted that the intertidal in- 

 dividuals were "as a rule smaller than those living in the soil 

 which is a little above the reach of the tide, but in earth which 

 is nearly saturated with salt water." 



Standing bodies of fresh water are absent in Bermuda. Coe 

 consequently held that this particular species, at least, repre- 

 sents a land nemertean which has almost certainly been derived 

 directly from a marine ancestor, and not, as Montgomery (1895, 

 p. 483) had argued for the generality of land nemerteans, from 

 a fresh-water form. 



During the past several years I have repeatedly encountered 

 G. agricola in a type of habitat which is significantly different 

 from that recorded for this nemertean by the observers just 

 quoted. In the neighborhood of every large or small mangrove 

 "creek" or swamp which I have examined, the worm has been 

 found, in relatively considerable quantities, well below low-water 

 mark even at spring tides. The species occurs in the localities 



i Contributions from the Bermuda Biological Station for Research, No. 76. 



