Reports & Proceedings — Geological Society of London. 41 



that the disused outlet is probably the older of the two, gives reasons 

 for believing that both outlets were in use perhaps simultaneously 

 during the latter part of the Grlacial Period, when a glacier filled and 

 overflowed the basin of the Hafslo Lake. 



The author describes some giants' kettles and other examples of 

 erosion by water, which for various reasons he believes to date from 

 a time when the glacier extended to the places where they are now 

 found, and it is suggested that they were the work of a river flovving 

 under the ice or between the ice and the rock. 



2. "On the genus AulophpUum." By Stanley Smith, B.A., M.Sc, 

 F.G.S., Clare College, Cambridge. 



Aulophyllum is a genus belonging to the Clisiophyllid group. It 

 is found in the Upper Beds of the Carboniferous Limestone Seiies 

 in Britain and on the Continent. It appears in the lower part of 

 tlie Bihmophyllum zone (D^), becomes common in the middle sub- 

 division of the zone (D3), and is plentiful in the highest limestones 

 investigated (D3). 



The coral was first described by David TJre, in 1793, as Fungites ; 

 the genus was established by Milne-Edwai'ds & Haime in 1850. The 

 author includes in this genus Thomson's genus Cyclophyllum. The 

 genus is described in detail, and then the ontogenesis is discussed. 

 The development of the various items of coral anatomy is first treated ; 

 and the author subsequently deals with the growth of the coral 

 considered as a whole, six stages being recognized by him. The 

 forms found in D]^ do not advance bej'ond stage d. 



Structural variation is then considered. The author regards all 

 the species previously described as variations of the same species, but 

 recognizes several well-marked types and a number of time mutations. 

 Many specimens of the coral display the phenomenon of rejuvenescence. 

 The structural changes observed are described, and the nature of the 

 rejuvenescence is briefly discussed. 



Becemher 4, 1912. — Dr. Aubrey Strahan, F.R.S., President, 

 in the Chair. 

 The following communications were read : — 



1. "On the Lower Palgeozoic Bocks of the Cautlev District 

 (Yorkshire)." By John Edward Marr, Sc.D., F.R.S., Y.P'G.S. 



The following classification is suggested for the Ordovician rocks 

 of the district : — 



fAshgill Shales. 

 Beds above the Volcanic Group. "j 

 Contemporaneous Volcanic Group. V Staurocepliahis Beds. 

 Beds below the Volcanic Group. J 

 Phacops robertsi Beds. 

 Cakadocian. Cahpnene Beds. 



The Phacops and Cahjmene Beds are remarkably similar in litho- 

 logical characters (dark calcareous shales and impure limestones), but 

 the palseontological change is at the top of the Ccdymene Beds, and the 

 fauna of the Phacops Beds is allied to that of the succeeding strata. 



In addition to other fossils, the Ashgillian strata contain graptolites, 



