156 
the same as the European P. fuitans, Roth., an earlier name, 
and running with us into several peculiar forms. 
Spec. 4; Am., from N. J., Ky. and Cal. 
27. P. lucens, L. Spec. 6; one from -Am., with no locality - 
marked; one from Cubaand four from Eu.; all excellent spec. 
28. P. marinus, L., (P. filiformis, Pers.) Spec. 5; one 
from the Yellowstone Park, *one from Lake Seneca, N. Y., 
one from Mich. and two from Eu. 
Var. (?) occidentalis, Robbins. Two spec. from Utah and 
Nevada, from the original spec. on which Robbins founded the 
variety. 
29. PP. mucronatus, Schrad. (P. pusilins; L.; var, mayor, Fries.) 
Spec. 2; both from Eu. * One spec. from ake Seneca, N. Y. 
30..- P. natans, Li: Spee; 107, Am; from ,Ni-J..to.7the 
Pacific Coast. *Spec., Ex. Herb. Dr. Robbins; for., Cont. Eu. 
There are also two doubtful forms; one from the Corean Archi- 
pelago, and one from India, coll. Hook. fil. and Thomson, which 
are labelled P. matans, having small elliptical leaves, and which 
may be forms of this species, but fruit is lacking to settle the 
matter. 
* Var. prolixus, Koch. One spec. Ex. Herb. Dr. Robbing 
A mere form growing in swiftly running water. 
P. Niagarensis, Tuckerm., vid. P: pauciflorus. 
31. PP. néttens, Webber, labelled “P. curvifolium,” but P. 
curvifolius, Hartm., is only a form of P. nitens, Web. For. sp.; 
one spec. from Eu. This spec. is a very fine one with floating 
leaves and good fruit, neither very common with this sp. 
32. P. Oakesianus, Robbins. Spec. 4; N.J; * type spec. 
Ex. Herb. Dr. Robbins. 
33. PP. obtusifolius,M.and K. Spec. 3; all for., France and 
Gr. Brit.; * one spec. from Sweden and others Ex. Herb. Dr. 
Robbins. 
34. PP. ochreatus, Raoul. Spec. from New Zealand, where 
alone the sp. occurs. 
pe pauciforus, Pursh. Spec. 19; N. Eng. to N. Mex. ; 
*spec. Ex. Herb. Dr. Robbins. : 
Var. Niagarensis, Gray, (P. Niagarensis, Tuckerm.) Type 4 
spec. from Prof. Tuckerman, coll: at Niagara Falls, but destitute — 
