258 R. MW. Brydone—New Chalk Polyzoa, ete. 
parallel to N.S. 1, until it falls so low as to pass through M.P., as at 
C.D. Then that part of the nival surface beyond M.P. will not be in 
the same plane with C.D., but will be horizontal nearly, or may even 
rise in the contrary direction if the outer ridges like K. are too small to 
cause by their own mass a marked increase in the precipitation (Fig. 8). 
This break will be maintained as the nival surface continues to fall. 
Case 2. As N.S. falls M.P. is depressed to the same extent, but 
the amount of precipitation remains constant. In all the new positions 
N.S. remains parallel to N.S.1. The supply of firn in the high ground 
is much reduced. 
Case 3. As in the last case M.P. falls at the same rate as N.S., but 
the amount of annual precipitation is much increased. 
Case 1 seems to be inconsistent with parallelism of the nival planes 
through all stages of glaciation. Seeing, however, that the zone of 
maximum precipitation stands in winter at the level of 1000 metres 
or lower,! this difficulty would vanish if it could be shown, as Penck 
suggests,’ that during the ice period the precipitation took place 
mostly in the coldest part of the year. But with this modification 
case 1 is open to the same objection as the following one. 
The hypothesis that N.S. and M.P. rise and fall in company is the 
most probable one. Case 2 does not, however, provide for a supply of 
ice sufficiently copious to fill the lower reaches of the valley up to or 
even above the level of the local snow-line, as seems to have happened 
in the Inn Valley during extremes of cold.? 
It remains to consider whether case 3, which would account for 
some of the most salient facts of Alpine glaciation, is admissible. 
EXPLANATION OF PLATES. 
Prate XIX. 
Fig. 1. Corries on the north slope of the ridge between Schafseiten Spitz (2604 
metres) and Bendelstein (2422 metres). From a point on the slope of 
the ridge east of Mieselkopf, distant about 6 km. Looking south. 
Fig. 2. The horizontal surface a little above the middle line of the picture, probably 
a plain of nival denudation, is held to indicate a former level of the floor 
of the Griibl, View taken from a point about 2100 metres above sea 
on the slope under the Schoberspitz, distant about 1 km. Looking 
south-east. 
Pirate XX. 
Fic. 3. Wall of serpentine blocks forming an almost complete girdle round the 
Reckner ridge at a level of 2600 metres and upwards. From a knoll in 
the Upper Tarntal 2600 metres above sea, distant about 0°75 km. 
Looking south-east. 
TII.—Nores oN NEW OR IMPERFECTLY KNOWN CHatk Poxyzoa. 
By R. M. Brypong, F.G.S. 
(PLATE XXI.) 
(Continued from the April Number, p. 147.) 
Mempranivora Woopwarpi,‘ nov. Pl. XXI, Figs. 1-3. 
Zoarium free or adherent, always unilaminate. 
Zowcia large, subpyriform, with broad margins sloping slightly 
inwards and expanding at the foot into a short front wall; areas 
1 J..Hann, Handbuch der Klimatologie, 1905, p. 262. 
2 Penck & Briickner, loc. cit., p. 1145. 
3 Loc. cit., p. 268. 4 Dedicated to the Editor. 
