42 Reports & Proceedings—Geological Society of London. 
would be too spongy in structure to resist the pressures to which they 
had undoubtedly been subjected. He also compared its mode of 
occurrence with that of quartz in a granite, and thought that the two 
were quite analogous. 
Mr. Peter Macnair, F.R.S.E., F.G.S., read a paper on ‘‘ The 
Horizons of the Type-specimens of Dithyrocaris tricornis and 
D. testudinea’”’. He detailed what was known as to the discovery 
of these interesting fossils, and pointed out that, while the facts 
connected with the East Kilbride occurrences were well ascertained, 
there was confusion with regard to the exact locality from which the 
Paisley specimens came and their horizon was not known. He stated 
that he had recently found specimens in an old dyke and an old house 
built of a peculiar limestone near Arklestone, Paisley, and showed 
that this material must have come from certain old quarries, now 
obliterated, and that these quarries must have been opened in the 
Blackbyre Limestone. 
Mr. R. G. Carruthers, H.M. Geological Survey, said that he quite 
agreed that these specimens must have come from a peculiar bed 
lying at the top of the Blackbyre Limestone at Arklestone, and 
congratulated Mr. Macnair on having settled a question that had 
been for so long a source of discussion. 
I1.—Grotoeicat Soctery or Lonpon. 
1. November 17, 1915.—Dr. A. Smith Woodward, F.R.S., President, 
in the Chair. 
Mr. John Parkinson gave an account (illustrated by specimens 
and lantern-slides) of the Structure of the Northern Frontier 
District and Jubaland Provinces of the East Africa Protectorate, 
made by him while conducting a water-supply survey for the 
Government of the Protectorate. A floor of gneisses and schists, 
among which the Turoka Series of metamorphosed sediments 
was found at several places, is overlain on the western side by 
lavas, including those arising from the volcanoes Kulal, Assi 
(‘Esie’ of the maps), Hurri, Marsabit, etc., and by probably older 
lava-fields, which together extend as far'as long. 39° E. On the 
south, it was found that the lavas north of Kenya reached the Guaso 
Nyiro, leaving ‘inselberge’ of the crystalline rocks in their midst, 
but that a high gneiss country extended north-westwards from 
lat. 1° N. and long. 38° E. to within a short distance of Lake Rudolf. 
Eastwards the Coastal Belt of sediments proved to be of Upper 
Oxfordian age and to extend to long. 403° KE. (west of Hil Wak), 
and these were lost southwards under the great alluvial plain of 
Jubaland. 
At intervals throughout the alluvial plain ard lying in hollows 
in the Jurassic rocks, disconnected exposures were found of soft 
calcareous sandstones or limestones (Wajhir, Eil Wak), the age of 
which cannot now be definitely fixed. 
Evidences of the desiccation of the country were, it was thought, 
shown (1) by the Laks or. water-channels characteristic of Jubaland, 
which contained surface-water only during the rainy season and then 
