On New Genera and Species of Nyctaginacec. 259 
Under such circumstances glaciers might descend to the sea-level, 
Where the configuration of the mountains should be sufficienly 
favorable to their descent, and supposing the sea to stand at such 
atelative height as to reach the bases of the mountains. ‘That 
this was the case, I have little doubt; for with the conviction 
that an enormous erratic block like the pierre a bot, above Neuf- 
chatel, must have been transported across the valley of Switzer- 
land by floating ice, I think it most probable that the whole Al- 
= region was, at the glacial period, 2000 or 3000 feet at least 
Wer than its present level; so that the sea might not only ex- 
tend to the base of the Alpine range, but might also penetrate 
into many of its lower valleys. 
_ Thus it appears from this investigation, that the same condi- 
tions which would produce glaciers on our Welsh and Irish moun- 
tains, descending to the level of the sea from a snow-line from 
1000 to 1500 feet above that level, might also produce similar 
Phenomena in the Alps with a snow-line 5000 or 6000 feet above 
the ‘sea, In more northerly regions there would, of course, be 
ho difficulty in accounting for the existence of similar glaciers. 
(To be continued.) 
_[Norr.—The Map which we have added to this volume in 
illustration of Prof. opkins’s paper, is a copy of one of the iso- 
“ermal charts of Dove—that for January ; except that we have 
made it throughout a winter chart by substituting for the January 
lines south of the equator the July lines, July being midwinter 
i the Southern hemisphere. The positions over Europe and 
the Atlantic of the lines of 32°, 23° and 14° in Prof. Hopkins’s 
hypothetical cases, are shown by interrupted lines connecting 
Dove's lines (the dotted lines) of the same name.—Ebs. | 
Pe 
Amr. XXXI.— Brief Characters of some New Genera and Spe- 
Kd Nyctaginacea, principally collected in Texas and New 
¥ Mexico, by Cuartes Waieut, Esq., under the direction of 
Col. J. D, Granam, U. 8. Topogr. Engineers, late Chief of the 
eI Scientific Corps of the Mexican Boundar? Commission; by 
“84 Gray, M.D. 
ACLEISANTHES, Nov. Gen. 
itvolucrum nullum. Perigonium tubulosum vel tubzeforme, 
bo patulo 5-angulato. Stamina sepius 5, inclusa. Stylus 
oak €xsertus : Stigma peltatum leve. Fructus ovoideus vel * 
i, andracens, 5-10-costatus. Embryo conduplicatus, albumen 
bys sum includens; cotyledone interiori minore.—Herbe radi- 
“ibus tuberosis caulibus decumbentibus vel diffusis; foliis op- 
