536 R. Mountford Deeley—The Ice Age 
TORNQUIST (A.). 1901. ‘* Uber mesozoische Stromatoporiden’’: Sitz. k. 
preuss. Akad. Wiss., pt. ii, pp. 1115-1123. 
TRAUTH (F.). 1911. ‘‘ Die Oberkretazische Korallen-Fauna von Klogsdorf in 
Mihren’’: Zeit. Mahr. Landesmus., vol. xi, pp. 104, with 4 pls. 
Vouz (W.). 1904. ‘‘ Zur Geologie von Sumatra’’: Geol. Pal. Abh., Jena, 
vol. x, pp. 87-196, with 12 pls. 
Wo.uaston (A. F. R.). 1914. ‘‘ An Expedition to Dutch New Guinea”’ : 
Geogr. Journ., vol. xliii, pp. 248-73, with 3 pls. and map (p. 364). 
EXPLANATION OF PLATES XXI-XXII. 
PLATE XXI. 
1. Actinacis swmatraensis (Tornquist). No. 14. Part of transverse section 
of corallum, x 6 diam. 
2. A. maitlandi, n.sp. No. 20. Fig. 2a, part of transverse section of 
corallum, x 6 diam.; Fig. 2b, part of polished surface of corallum, 
horizontal section, x 6 diam. 
3. A. maitlandi, n.sp. No. 37. Part of transverse section of corallum, 
x 6 diam. 
4. Kobya hemicribriformis, n.sp. No. 35. Part of polished surface of 
corallum, nat. size. 
PLATE XXII. 
1. Montipora antiqua, n.sp. No. 36. Fig. 1a, part of polished surface of 
corallum, horizontal section, x 3 diam.; Fig. 10, part of polished 
surface of same specimen, vertical section, x 3 diam. 
Porites deshayesana, Mich., var. wmequisepta, n.var. No. 23. Fig. 2a, 
part of surface of corallum, x 10 diam.; Fig. 20, part of surface of 
corallum, x 23 diam. 
The locality of all the specimens is the Upper Fly River, New Guinea. The 
species figured are from the Eocene, and probably Middle Eocene, except 
Actinacis sumatraensis, which is Upper Cretaceous. 
NoTE.—Since the first part of this paper was printed we have received 
from Mr. F. Chapman a description of Aquitanian limestones with Lepido- 
cyclina and Heterostegina, which were collected at Bootless Inlet, British New 
Guinea, by Mr. J. E. Carne (Chapman, F. 1914. Description of a Limestone 
of Lower Miocene Age from Bootless Inlet, Papua. Journ. Proc. Roy. Soc. 
N.S. Wales, vol. xlviii, pp. 281-301, pls. vii—ix). 
November 17, 1916. 
bo 
IJ.—Tue Cavsze or rae Ick Acr anp Guacter Frucrvations. 
By R. M. DEELEY, M.Inst.C.H., F.G.S. 
({\HE fluctuations which take place from time to time in the lengths 
of glaciers are extremely interesting to the glaciologist; for 
there are good reasons for believing that the meteor ological conditions 
which give rise to the lesser oscillations of glaciers are generally of 
the same character as those which produced the great secular changes 
of climate which occurred in past ages. 
At the present time there are no theories purporting to account 
for the more important glacier fluctuations. The one assumes that 
they are due to increased precipitation per square yard, whilst the 
other attributes the phenomena to a general lowering of the tempera- 
ture of the atmosphere, the precipitation per square yard remaining 
practically unaltered. Iu the case of the latter theory, the variation 
in the amount of ice formed is considered to be due to the lowering 
of the snow-line and consequent increase in the size of the mévé areas. 
It is evident that within historic times changes of climate have 
occurred, for we have records of very considerable advances and 
