NOTES ON POTAMOGETONS. 995 
linear, 1-3 in. long, 1-14 in. poate 3- veined ; ea outer slender 
s- 
h 
duncles sle oe tse 14-24 in. ae spikes 4-6 lines Pine: with 
6-9 fru its. Sepals ovate, “with a rounded base. Fruit 24 lines by 14 
in. broad, ovate (or slightly obovate), nearly flat on the sides, and 
impressed with a shallow depression; the 3 keels oats defined 
by raised lines on the smooth surface of ie ventral face of the 
fruit, and without any tubercules ; toak prominent on the dorsal 
P. sprrinius Tuckerman in Sill. Journal, 2nd series, vol. vi 
p. 228 (1848). Dr. Morong, in his Mon. Fl. Fnarinth Naiad 
queries my reference of P. Zetterstedtit Wallman (Schl. & Mohl. 
Bot. Zeit. 1. 256 (1848), as belonging to the above plant. While a 
believing it does so, T cannot say I have seen a specimen to pro 
it. But it is of secondary importance, if I am right in believing that 
Tuckerman’s plant must bear the name of P. dimor phum Rafinesque © 
i 1817). 
€); 
. hybridus Michx. (1 08) In 1828, in his Flora of N. America, 
t. 84, vol. iii., he figured his oes and the plate seems to me to 
represent r: ‘spirillus, if there is any difference aes that and 
plant is different from his elt ras and hence from hybridus of 
Michx., and preferred the name P. dimorphwm for it ; and it seems 
to me that it must bear hal name, and that Tuckerman’s becomes 
a synony 
As Dr. Morong uses P. diversifolius Raf. for P. igs Michx., 
because the latter had been used by Thuillier (or rather Pentagna) 
for P. heterophylius Schreb., it follows that Barton's diversifolius 
will become a synonym of P. dimorphum Raf. 
But the “law” that is desired to be forced on us, “that any 
species or variety that has been so named, under any other species 
or variety, cannot be used in the same genus,”’ will be of somewhat 
difficult application. Students certainly will never know, and even 
monographers will not be safe, as proved by Dr. Morong’ s own 
work, where he must (by his own law) change the names of at least 
e American authors (Seay &c.) refer Barton’s diversi- 
Be not see how this could have 
been done with Barton’s plate in existence, = his and Rafinesque’ : 
positive declaration to the contrary. The e facts cannot be put 
‘ae. C. 
P, riurrans Roth, Fl. Germ. i. p. 72 (1788): ii. p. 202. In his 
recently published Monograph, Dr. Morong remarks that he hesi- 
tates to identify P. Lonchites of Tuckerman with the plant usually 
