40 Reports and Proceedings — 



terrace, it drained away quietly, at any rate until it receded from 

 Upper Glen Roy. 



In discussing Nicol's objections, lie maintains that notches would 

 not be cut at the level of the cols, and observes that the discrepancy 

 between the heights of the terraces and those of the cols has pi-obably 

 been increased by the growth of peat over most of the ground about 

 the watersheds. 



The horizontality of the terraces is stated to be a fact, and cases 

 are given where waterworn pebbles are found in connexion with the 

 " roads," these being especially noticeable in places where the south- 

 west winds would fully exert their influence, and the structure of 

 the terraces is considered to be such as would be produced at the 

 margins of ice-dammed lakes. Further information is supplied con- 

 cerning the distribution of the boulders of Glen Spean syenite. These 

 are found on the north side of the Spean Valley at the height of 2000 

 feet above the sea and 1400 feet above the river, and fragments of 

 the syenite have been carried towards the north-east, north, and 

 nortli-west. 



In an Appendix, the author discusses Prof. Prestwich's remarks 

 on the deltas, and his theory of the formation of the terraces. 



11. —Nov. 25, 1891.— Sir Archibald Geikie, D.Sc, LL.D., F.R.S., 

 President, in the Chair. — The following communications were read : 



1. "On the Os pubis of Polacanthus Foxi." By Professor H. G. 

 Seeley, F.R.S., F.G.S. 



Hitherto the evidence of the systematic position of Polacanthus 

 has not been very precise. The author has detected the missing 

 pubis as an isolated specimen. This he regards as the anterior 

 portion of the left pubis, and appends a full description of the bone. 

 He furthermore gives a critical account of our knowledge of other 

 pelvic bones of the genus, and is led to associate Agathmmns, Cra- 

 tcEomus, Omosaurus, and Palacanthus in near alliance, in the Scelido- 

 saurian division of the Order Ornithiscliia. 



2. " A Comparison of the Red Rocks of the South Devon Coast 

 with those of the Midland and Western Counties." By Professor 

 Edward Hull, LL.D., F.R.S., F.G.S. 



The author believes, with Dr. Irving, that the Red Rocks of 

 Devonshire are representatives of the Permian and Trias, which 

 occupy so large a portion of the district bordering Wales and Salop, 

 and which extend into the Midland Counties, and comments on the 

 remarkable resemblance between the representative beds on either 

 side of the dividing ridge of Palaeozoic rocks which underlies East 

 Anglia and emerges beneath the Jurassic strata in Somersetshire. 



He believes that the breccia forming the base of the series in the 

 Torquay district is a representative of the Lower Permian division, 

 but differs from Dr. Irving, in assigning the red sandstones and 

 marls of Exmouth to the Trias, and not to the Permian, as that author 

 has done. He compares them with the Lower Red and Mottled 

 Sandstones, and regards the Marls as of local origin, thus causing 

 the beds to diverge from the normal type. 



