950 
by Karsch the name Hollandella. I am, like 
Dr. Sharp, unable to recognize characters of 
family value, and the distinction between the 
group, typified by the genus in question, and the 
generally recognized constituents of the family 
Arbelidee appears to me to be of not more than 
subfamily importance. From this standpoint 
the nomenclature would be as follows: Family 
Arbelidze, subfamily Hollandelline, genus Hol- 
landella, ete. 
I imagine that the change which I propose 
will not be displeasing either to Dr. Karsch, 
the learned custodian of the Royal Museum of 
Natural History in Berlin, or to my friend the 
Director of the Carnegie Museum. 
THEO. GILL. 
WASHINGTON, May. 1901. 
CURRENT NOTES ON PHYSIOGRAPHY. 
U. S. GEOLOGIC FOLIOS. 
THE folios of the Geologic Atlas of the United 
States continue to furnish an unrivaled source 
of physiographic as well as of geologic informa- 
tion. Among the more recent, the following 
may be noted: The Monterey folio (Va., 
W. Va., Darton) exhibits the crowded Appa- 
lachians bordering the Allegheny plateau, a 
district of strongly corrugated strata now re- 
duced to ridges and valleys of anticlinal, syn- 
clinal and monoclinal structure. Bristol (Va., 
Tenn., Campbell) includes a monoclinal belt 
with many overthrust faults, characteristic of 
the Appalachians in Tennessee; the mountains 
here are nearly rectilinear, in contrast to the 
sharp-turning zigzags further northeast. Be- 
tween the mountains is an open country with 
many low ridges, once a lowland, but now dis- 
sected after a gently slanting uplift. Standing- 
stone (Tenn., Campbell) presents a portion of 
the Cumberland plateau, with its ragged west 
ern escarpment descending to the ‘highlands,’ 
themselves dissected by streams that go to the 
lowlands next west. Uvalde (Tex., Vaughan) 
contains a part of the Rio Grande plain border- 
ing the Edwards plateau whose dissected es 
carpment appears on the north. The plateau 
has yielded sand and silt with which the broad 
valleys of the plain are washed; here the 
streams frequently disappear and reappear, the 
Nueces river being an unusually large example 
SCIENCE. 
[N. S. Vou. XIII. No. 337. 
of this kind. Elmoro (Col., Hills) shows the 
broad Plains that front the Rocky mountains 
near Trinidad to be surfaces of denudation, 
remnants of the removed strata being preserved 
under the lavas of Raton mesa; the Plains are 
now somewhat trenched by the’streams. Fort 
Benton (Mont., Weed) gives another illustration 
of the great denudation by which the Plains 
have been formed, as testified to by the isola- 
tion of the Highwood mountains, an embossed 
body of dissected lavas and dikes; the larger 
river valleys of to-day are here sharply sunk 
beneath the Plains. Little Belt (Mont., Weed) 
affords an excellent illustration of the topo- 
graphic consequences of the Neocene warping, 
for the modern deposits of Smith river basin 
(described as lacustrine, although consisting of 
irregularly bedded sands and loose conglomer- 
ates). overlap unconformably upon both the de- 
nuded central and marginal rocks of the greater 
Laramie deformation. Like the Highwood 
mountains, south of Fort Benton, the Crazy 
mountains, a network of dikes, here testify to 
the great erosion of the Plains that they over- 
look. Absaroka (Wyo., Hague) is character- 
ized by the superb dissection of a high plateau 
of lavas and volcanic breccias; the whole region 
has been glaciated, and some of the valleys 
heading in great cirques seem to show glacial 
scouring in their smooth-sided, trough-like 
forms. Tacoma (Wash., Willis and Smith) in- 
cludes examples of channels of ancient glaciers 
between uplands largely composed of drift; the 
channels now being invaded by the sea from 
without and by alluvium from within; the 
sounds are thus explained by retreat of the ice 
and not by depression of the land. Mother- 
Lode (Cal., Ransome) exhibits parts of the up- 
lifted and dissected peneplain of the Sierra 
Nevada : it was strewn with gravels and flooded 
with lavas and volcanic conglomerates before 
uplift; itis now trenched by canyon-valleys. 
A few eminences surmount the uplands ; several 
lava-capped table mountains standing up with 
long even-crested tops between the valleys. 
RIVERS OF EAST YORKSHIRE. 
THE subject of the Sedgwick essay announced 
by Cambridge University for 1900 was on the 
dependence of water-courses upon geological 
