110 Dr. C. W. Andreus — Elephant Molar from Khartum. 



The presence of titanium was also proved by the j'ellow colour 

 obtained with peroxide of hydrogen in the sulphuric acid solution, 

 and by the blue colour obtained with tin in the hydrochloric acid 

 solution. The density was determined as 4-72. 



Hcematite. — A few rounded reddish-black grains of this mineral 

 were found in sample B. They are characterized by a brilliant 

 metallic lustre on the surface, but are partially converted to limonite 

 in the interior. Hence the low densitj' obtained, viz. 4 '6. The 

 streak was cherry-red. 



Magnetite. — A few small black grains with metallic lustre are 

 present in sample B. They are strongly attracted by a small bar 

 magnet. 



L-on Pi/rites. — This mineral is present in both samples in irregular 

 fragments, but is more abundant in sample A. 



Diopside. — One grain of this mineral was found in sample B. It is 

 green and translucent with a refractive index of 1'69. It shows the 

 rectangular prismatic cleavage and two pinacoidal cleavages, one of 

 which appears to be a diallagic parting. The density was found to be 

 3'4. It is probably the chrome-diopside variety. 



JEpidote. — One cleavage fragment of this mineral was found in 

 sample A. It presents the characteristic pistachio-green colour and 

 basal cleavage. 



From this examination it is evident that the bulk of the particles 

 making up the finer material of the gravels consists almost entirely of 

 minerals that possess a high capacity for resisting weathering — such 

 as quartz, the various oxides of iron, corundiim, kyanite, garnet, 

 tourmaline, zircon, and diamond. On the other hand, the readily 

 decomposable minerals, such as members of the felspar, amphibole, 

 and pyroxene groups, are, with one exception, conspicuous by their 

 absence. The obvious conclusion to be dz'awn from this fact is that 

 these alluvial gravels are not derived directly from the crystalline 

 rocks, but come intermediately from the lateritic weathering products 

 by which these are replaced at the surface and which would naturally 

 fall an easy prey to river erosion. 



IV. — Note on the Molar Tooth of an Elephant from the Bed 

 OF the Nile, near Khartum. 



By C. W. Andrews, D.Sc, F.E.S. (British Musemn, Nat. Hist.). 



IN sinking the caissons for the construction of the bridge over the 

 Blue Nile near Khartum, a considerable number of bones have 

 been found, from time to time, in the alluvial beds, at ^ depths of 

 60-68 feet below the level of low Nile. These specimens were 

 obtained by Messrs. Hinckley, Stephen, and Le Bailly, and are now 

 deposited in the collection of the Geological Survey of the Sudan at 

 Khartum. 



Most of the specimens have been sent to me for determination 

 by Mr. G. W. Grabham, Geologist to the Sudan Government. 

 The bones are all black or nearly black, very heavy, and highly 

 mineralized through the infiltration of silica and iron, so that they 



