64 Cincinnati Society of Natural History. 
Michigan, Wisconsin, Iowa, nor Kansas. Gray considers it to have 
been introduced by man. In Europe it is said not to occur north of 
latitude 55 deg. Potentilla argentea is in the same category. It is 
not known to pass north of latitude 50 deg. in America, although it 
reaches to 70 deg. in Europe. Myosotis arvensis “is not common here, 
and has probably been introduced.”’* In Europe, it is found as high as 
70 deg. latitude.t . 
Subularia aquatica is a rare plant in North America, having been 
. found only in Maine and New Hampshire.t “From its size, aspect 
and place of growth, it is exceedingly liable to be overlooked” (Gray). 
In Europe, it is found as far north as 72 deg. latitude.§ Sagina apa- 
tella is found in “ Dry soil, N. Y., and Penn. to Ill., scarce, seemingly 
native.” || It is not given in catalogues of plants of Buffalo, Chautau- 
qua, Dist. Columbia, Michigan, Ohio, Iowa, Kansas, Wisconsin, nor 
Canada. It must be, therefore, either very scarce or easily over- 
looked, and has most likely been introduced in some few places. It 
does not extend further north than latitude 55 deg. in Europe. 
The following ten species are all found in this country, at least as 
far north as latitude 50 deg., and none of them extend north of lati- 
tude 55 deg. in Europe. Their distribution is explained under the 
rule already laid down in regard to some species of List No. II. (ante p. 
59), only in this case they stop at 55 deg. in Europe, instead of extend- 
ing to 70 deg. as do the former ones. : 
Sagina procumbens. Centunculus minimus. 
Circza lutetiana. Rumex maritimus. 
Scrophularia nodosa. | Carex muricata. 
Salsola kali. Carex levigata. 
Lythrum hyssopifolium. Hordeum pratense. 
Of the following all are varieties of European species. Sometimes 
the species and variety are both found here, and sometimes the latter 
a 
only. In the former case, it is found that the variety is the more com- — 
mon to the southward, if not wholly confined there. In the latter case, 
we may consider that we have here cases in which the species has 
varied to a certain degree in the south and been maintained there, 
while the parent species has ceased to live at the north on account of 
the cold. These species are as follows : 
* Gray, Am. Jour.,/. c., p. 65. 
+ Watson, J. c., p. 65. 
t Gray’s Manual, p. 73. 
2 Watson, l.c., p. 191. 
|| Gray’s Man., p. 94. 
{ Watson, l. c., p. 195. K 33 
