694 General Notes. [ November, 
rostomata and subclass Gnathopoda. Having ourselves, from a study of 
’ the king crab and the tegument of the trilobites, and from the sugges- 
tions of Billings regarding the nature of the appendages of the trilobites, 
arrived at the conclusion that the trilobites most probably had jointed 
ambulatory limbs as well as membranous swimming appendages, it is 
gratifying to find what was before a matter of probability, actually dem- 
onstrated by the patient toil and well sustained energy of Mr. Walcott. 
The discovery of the nature of the limbs of trilobites “adds a fresh 
laurel,” to use a fossilized expression, to American paleontology. | 
Tue GREENLAND GLACIERS. — Amund Helland, of Christiania, Nor- 
way, made in 1875 a journey to North Greenland, and gives in the 
Quarterly Journal of the Geological Society of London (No. 129), the 
results of his comparisons of the glacial phenomena of that country with 
those of Norway. He has overlooked the writings of Americans who 
have visited Greenland, and he probably never saw the magnificent work 
in folio of our marine artist, William Bradford of New York, which con- 
tains many photographs of the Greenland glaciers, and possesses a g00 
deal of scientific value. Helland believes that “the thickness of the in- 
land ice near its border cannot exceed 250 metres, and is probably not 
more or is even less than 200 metres; but since its surface rises as we 
proceed inland, its thickness may possibly increase in that direction.” 
“The amount of precipitation in North Greenland seems to indicate 
indirectly the great extent of the inland ice; for where the glaciers are 
largest it is not considerable; at the colony of Jakobshavn the rainfall 
from July, 1873, to July, 1874, was 219.7 mm., from July, 1874, to July, 
1875, 183.7 mm. In the district of Umanak, where there are a number 
of great ice-fjords, the rainfall seems to be no greater ; yet here the gla- 
ciers are very large, one may say the largest known ; so that we can 
only account for them by supposing that they are supplied from a very 
extensive upland district on which there is a considerable snow fall, and 
thus that there can be little land in the interior free from ice. Be this 
as it may, there is no doubt that the ice-sheet extends into Greenland 
beyond the range of vision.” 
The fact, he says, that though the climate of Greenland is rather dry 
large glaciers are numerous, is not without geological importance, a 
showing that a great snow fall is not absolutely necessary for the glacia- 
tion of an extensive country. “It is also remarkable that the glaciers 
are supplied from an ice-field which, to a large extent at least, lies below 
the limit of perpetual snow.’’ He contends that Greenland is not à col- 
lection of islands, but a fjord land like Norway or the coast of 
erica. 
He found that the Jakobshovn glacier flows with a velocity greater than 
any that has hitherto been observed, the greatest daily motion observed 
being 22.46 metres, from July 8th, seven P. M., to July 9th, ten A- 5 
while the slope of the land is only half a degree. The maximum daily 
North 
e 
