Vol. 70.] MIOCENE OF THE YICTOETA STANZA., ETC. 131 



grey sandstone with angular and but slightly rolled fragments 

 (measuring up to an inch and a half in diameter) of pink and grey 

 gneiss, green andesite, and quartz, all derived from the country 

 farther east, which seems to point to fairly-close proximity of 

 the land. Here, too, at Kikongo, at the base of No. 12, another 

 bed of sandstone occurs, which is not found farther east. 



(2) The middle series (Beds 13 to 25) is much more varied in 

 character, and fossils are more frequent. In general, the tendency of 

 the clays to become red is very marked ; thin beds of travertine occur 

 at intervals, and sandstones and gravels prevail towards the base. 



Transitional conditions are indicated by No. 13, which consists 

 of about 5 feet of greenish-grey clay (sometimes speckled with 

 flakes of biotite), with intercalary layers of pink concretions. Some 

 fragmentary Chelonian remains (ribs and scutes of Trionyx) and 

 a larsre Artiodactvl astragalus were the onlv fossils obtained at this 

 horizon. 



The most persistent bed in the whole of the Miocene Series is 

 No. 14, which constitutes a marked physical feature, giving rise 

 to a nearly level terrace, fairly wide at Nira and forming the upper 

 edge of a small cliff. Typically this bed consists of a dull-red 

 hard marlstone, passing occasionally either into impure travertine 

 or more rarely into a soft clay. In places it is mottled red and 

 grey ; usually it is only 6 inches thick, but it may swell out to 

 18 inches, and is traversed by vertical joints filled with calcite and 

 limonite. The upper surface of the terrace presents the appear- 

 ance of an irregular pavement of bricks. At the extreme east 

 (Kikongo) it has lost its redness, and has become dark grey. It 

 is characterized by numerous casts of AmpuUaria ovata and 

 Lanistes carinatus, also opercula of the former, together with 

 fragmentary Chelonian and Crocodilian remains. A similar bed 

 yielding similar fossils occurs "with less constancy in the upper part 

 of No. 15, which consists of rapid alternations of red clay and thin 

 layers of pinkish- white calcareous concretions, somewhat resembling 

 losspiippchen. Probably they were formed by gentle currents 

 disturbing the deposits from calcareous springs in a muddy lagoon. 

 The redness of the clay is inconstant, and frequently passes into a 

 grey or greenish-grey. No. 15 thins out eastwards. 



Nos. 13, 14, & 15 form essentially a natural group (10 to 12 feet 

 thick) separated from a somewhat similar group (Nos. 18, 19, & 20, 

 8 to 12 feet in all), in which red clay predominates (with numerous 

 inconstant seams, 1 to 2 inches thick, of argillaceous travertine), by a 

 very constant horizon (1 to 2 feet thick) of Nos. 16 & 17. In No. 16 

 (see PI. XXI), a grey argillaceous sandstone, I found a very few but 

 interesting jaw-bones of a small new type of Hyracoid (Miohyrax^ 

 oswaldi), with AmpuUaria ovata, scutes of Trionyx and crocodile. 

 No. 16 overlies a sandy clay (No. 17), the last-named bed en- 

 closing an occasional seam of sandstone with similar Crocodilian 

 and Chelonian remains, all in a very fragmentary condition. 

 Fossil bones are a little more frequent in the lower part (Nos. 18> 



