80 



ON SEKPICULA OCCIDENTALS. 



consideration : the rules of priority are thereby broken, and ns there is 

 no Hydrilla verticillata, and no confusion can arise from using it, I 

 shall now propose that name for the Serpicula verticillata, L. fil. 



The Dammschen Sea, Wilna, and Lyck specimens of H. verticillata 

 include two forms ; one of these has long, almost linear-lanceolate, 

 slightly recurved, membranous leaves, plane at the margins, and with 

 long (often very long) internodes; it is commoner in the Dammschen Sea, 

 and rare near Wilna, growing in deep water ; this I call var. gracilis, 

 rejecting the earlier name, Pomeranica, because it is only geographical, 

 and the same variety is also found in India. The other form has some- 

 what lanceolate, attenuate, recurved leaves, more or less crumpled at 

 the margins, and of a thicker texture, having also much shorter inter- 

 nodes, which are hardly so long as the leaf; this form is found near 

 Wilna, and also in India and China ; I shall call this var. crispa, and 

 withdraw the earlier name of Lithuanica, as being too geographical ; it 

 grows in shallow water. The plant found by Herr Sanio* near Lyck, 

 is var. crispa, although more membranous than even the Wilna plants 

 usually are. 



I had early in this year suggested to Herr Sanio that Hydrilla verti- 

 cillata might occur in the lakes of Eastern Prussia, the plant having a 



decidedly eastern range, and I am rejoiced that my surmise has proved 

 correct. 



Bonn, December 1, 1856. 



These valuable observations settle the question of the assumed native 

 origin of the Anacharis Alsinastrum in England, that plant being un- 

 doubtedly Pursh's Serpicula occidental, a species not found in Europe 



and tropical America. 



World 



Hydrilla 



have been content, in a case of so much perplexity and confusion, to 

 have followed Dr. Caspary in adopting his new specific name of dentata, 



l & 



ithdrawu 



verticillata, we are bound to adopt the latter. In deference also to the 

 great service he has rendered in clearing up these obscure plants, bota- 

 nists will no doubt further adopt his names of crispa and gracilis for 

 the two varieties, though we do not think that those of Pomeranica and 

 Lithuanica were at all objectionable. Specific names do not necessarily 

 refer to characters in the plants themselves to which they are applied ; 



