( 'orre><2)oridence. 
:^,9T 
:sible in 1888, and am not aware that any facts recently ])r()ught to 
light would greatly affect then. 
Faithfully yours, F. A. Katheu. 
Xatural History ]\ruseum. 
London, S. AY., Nov. 18, 1892. 
CLASSIFICATION OF CEPHALOPODA. 
LIPOPROTOCON'CHIA. SOSIPKOT()COXCHI.\. 
Naltiloidea. Intermediate and Ammoxoijiea. Colechdea. 
Orthoceratidae (^. str.) 
Goinphoceratidiie 
Poterioceratidae 
A(-coceratidae 
Cyrtoceratidae 
Lituitidae 
Trochoceratidac 
Naiitilidae 
more ancestral Bactritidae Osteophora 
forms — Asellate Anlacoceratidae 
Endoceratidae Latisellate. and Xiphotmitliidae 
-•Vctiuoceratidae Angustisellate Belcimiitidae 
grades of Bclopteridae 
Goniatltes S])inilidae 
Families of Ammon- Sepiadae 
ites nnccitain. Chondrophora 
( M y o p s i d ) 
Beloteiitliidae 
T<nithidae 
Belemnoteutlii dae 
Loligidae 
Sepiolidae 
(Oigopsid) 
Octopodidae 
Pliilonexidae 
Cirrhoteuthidai' 
The Movements of Muir Glacier. — In accounting for the apparent 
discrepancy lietween Prof. Eeid's measurements of the movement of 
the Muir glacier and my own, in your notice of his important work, 
attention should have been called to one other point, namely, that we 
did not measure the same portions of tlie glacier. Professor Reid 
measured the motion only as far out from the edges as he could plant 
stakes ; but there was a quarter of a mile or more in the middle which 
he found it impossible to reach. The reason why he could not reach 
it was that that was the most rapidly moving part where conse- 
quently the crevasses were impassable. ]My base-line was on a level 
with the edge of the ice, so that we could recognize the ])innacles and 
domes and moraine-covered patches as they slowly moved past across 
the horizon. Mr. Baldwin and myself were very confident that we 
made no mistake in the recognition of these objects. Pi'ofessor Reid's 
base-line was several hundred feet higher up upon the mountain side 
than our line, so that in looking down upon the glacier he had not 
the same advantages for recognizing the pinnacles. Of course, a larger 
margin of error should be allowed for our observations than for his, 
since our angles were taken with a sextant and his with a theodolite. 
But on points nearer the shore our results were very nearly the same 
as his. Professor Reid has just returned from another expedition to 
the Muir glacier, and reports great changes in the appearance of the 
front. This year the front has assiuned almost exactly the shape 
which is shown in my i)hotographs of six years ago, while two years 
ago the contour of the front was entirely different. Professor Reid 
has brought back a large amount of important information about the 
whole system, but it is too early yet to publish the result . 
(Hirrllii, ()., Xor. 7, hS!L'. (i. FitEnEKHK W'kkmit. 
