OF XAIAS GBAMIXEA, TAR. DEU1.EI, 31 



given it tKe Tarietal name of DelUeij on accomit <rf a 

 stmctiEral pecoliaiity referred to on pages 46 and 69. 



II. The GExrs axd its Dirisioxs. 



Tke geoos gires its name to the natural order ^Naiadacese, 

 which is allied to the Potamogetonaces^ bat srstematists 

 are by no means agreed as to tbe respectire limits of 

 either family. Willdenow separated the groop to whidi 

 N. fframinea belongs finom Naias proper, nnder Iflie generic 

 name of Caulinia^^ on account of the male flowers not 

 haying the qnadxifid perianth of ^Taia* proper ; bnt Bob@rt 

 Brown lennited the two groups of Naias and Cimtsma into 

 Naias, lann. There is no doubt, howerer, that each of 

 these divisions forms a Tery natural group sharply sepa- 

 rated from the other by well-marked characters drawn 

 from the leaf, stem, and nruit. All these points hare been 

 carefblly worked out by Dr. P. Magnus in a work whicb 

 he modestly entitled ' Beitrage zur Kenntniss der Gattong 

 Najas, L.' (Beriin, 1870) ; and no one ?iz: zzl- : - . : r the 

 morpbology and anatomy of a plant of tIi- r: jiut 



admiring the minute and conscientious ii i^: ^:.r^::is ;f 

 this author. In preparing the following ii;:i- I l. r 

 referred again and again to this memonr, ana I caiiiioi 

 speak too highly of the help derived fi-^r; it. 



Dt. Ma^us gives the follc^T^Jiz - of tbe two 



subdivisions of the genus, viz. : — 



" § ErxA/AS, Asch. — Spine-teedi chiefly on the stem and 

 backs of the leaves. Flowers dioecious (? in all) . Anther 

 four-chambered (? always; . Seed-shdl consisting of a 

 many-layered stony parenchyma. C<Hiducting bundles of 

 the stem divided from the intercellular spaces by two to 

 three layers of parenchyma-cells. Leaf famished with a 



* ■ ^imasres de fArademie Bonis des SoetKes deBatiB. 1798. dsse de 



