POTAMOGETON IN THE ENGLISH LAKES 
7 
P. cmspus L. Hoclgson (Z. c .) considers this “a very common 
and widely diffused species,” and correctly, but it is certainly not so 
in the larger lakes. The form which has been named var. serratus 
Hudson, occurs occasionally both in Esthwaite Water and Hawes 
Water (G9«), but is uncommon or absent elsewhere in the lakes. 
P. pectinatus L. has been recorded (PL Cumb. 818) for Bassen- 
thwaite—probably in error. At any rate, we have not seen it there 
nor in any other lake up to the present. It is abundant in muddy 
calcareous tarns near the sea (<?. g. Urswick Tarn, v.-c. 69 b) and in 
the Cavendish Hock and Ormsgill Reservoir at Barrow. 
We have considered it advisable to confine the records given 
herewith to those of which we have personal knowledge, and have only 
cited others when they are admittedly incorrect or we are unable to 
confirm them. Owing to the immense area to be surveyed, and the 
fact that many of the species are entirely submerged, it may well 
happen that the list is not exhaustive. However, we have been 
engaged during the past 15 years in systematically examining the 
aquatic vegetation of the lakes, and during the past 3 years have 
visited some of them monthly, and all of them several times in the 
year. We feel, therefore, that the list may be accepted as a fair 
representation of the distribution of the various species of Potamo- 
geton in the English Lakes at the date of publication. 
THE TYPE-SPECIES OF PTERIS. 
Br William R. Maxojst. 
Several contributions to the pages of this Journal of late have 
served to focus attention sharply upon certain features of the present 
International Rules of Botanical Nomenclature that many writers 
(both British and American) look upon as objectionable, and to fore¬ 
cast eventual changes in the rules in several important respects, 
notably in the typification of genera by a definite “method of types.” 
There is, obviously, general desire for an agreement in which all may 
unite. On the American side this is due in part to a strong drift 
away from the rigid provisions of the so-called American Code of 
1907, and may be credited largely to the efforts of the “ Committee 
on Nomenclature” of the Botanical Society of America, summarized 
in their two reports of 1919 and 1921 ( Science , n. s. xlix. pp. 833— 
386; liii. pp. 312-314). “ First species ” rules and the like having 
failed from very arbitrariness, wide modification in the mechanism 
of applying the method of types is now urged. It has even seemed 
necessary to the committee to affirm that “ rules of nomenclature 
should commend themselves as being reasonable,” and that “ they 
should be as definite as is consistent with reasonableness.” However 
axiomatic, this appears not to have been written in a vein of conscious 
irony. At any rate, the recent effort has clearly gained support for 
the type-basis idea in generic nomenclature, and it is coming to be 
recognizee! very generally that this concept is not at odds with the 
principles of the International Rules. To a great majority of American 
