304 miss c. a. .raisin on [May 1903, 



the specimens. He reports that there is not a trace of a spicule to be 

 seen, and consequently it cannot be decided whether the organism 

 is a calcisponge or not. The fine-grained muddy groundmass, 

 speckled with small crystalline grains of dolomite, contains some 

 minute organisms. The lithological and fossil contents of these 

 limestones make it probable that they are of Cretaceo-Eocene age, 

 or possibly Miocene. 1 



One limestone ' near the summit of the Pass ' from Jigjiga to 

 Abyssinia, found 4 in enormous blocks, doubtless fallen from above,' 

 is white or cream-coloured. It is crowded with a gasteropod (| to | 

 inch long), doubtless a Turritella* and in the cut slice a few frag- 

 ments of a polyzoan occur. Calcite-crystals line the chambers of 

 the Turritella, and border small fragments and some oolitic grains. 



Another limestone, generally fine-grained and muddy, is crowded 

 with organic fragments, which stand out on a weathered surface. 

 The specimen from the hill south of the camp, near Colluby, 

 contains Miliola, Tesotularia, Oalcarina(?), and some oolitic grains. 



The rock at the ' Pass between Colluby and Galimala (?) beneath 

 basalt ' furnishes a slightly-brecciated slice, with a cement of clear 

 crystalline dolomite. It encloses brownish oolitic grains and 

 numerous fragments of Lithothamnion, of an echinoderm-plate or 

 ossicle, and a polyzoan (?). 



Chert. — A small flake (probably artificial) of whitish chalcedonic 

 chert was brought from between Jigjiga and Sobolo or Jefa Medr. 

 It is crowded with sponge-spiculcs, which are embedded in pale 

 brownish opaline silica, and are often chalcedonized. 



Y. Specimens bkougiit back by Lokd Lovat. 3 



These were taken chiefly from four localities. The journey was 

 made from Addis Abbeba (about lat. 9° N.) to Dessieh (about 

 lat. 11° N.), and the return was by a kind of loop-line to the east. 



(1) Ahiafedge. — Along the gorge, a section exposed below the 

 soil (6 feet) of the plateau showed a felstone, 10 to 30 feet thick, 

 intercalated between two layers of basalt. Then two successive 

 shoulders, projecting into the valley, consist mainly of a sheet of 

 basalt 200 feet thick. The rock is dark-brown, sometimes ' flaky,' 

 or containing small amygdales or pinhole-cavities filled with a green 

 or brown serpentinous product. A ' weathered rock 40 feet thick ' 

 was passed, apparently a gritty tuff, and successive sheets of basalt, 

 one with vesicles partly filled by analcime, one columnar and 

 vesicular, one probably spheroidal. The most interesting specimen 

 is described as 10 feet of ' coal-like rock,' hard and splinter)'. The 

 fragment is cracked and brittle, and contains a few amygdales. It 

 is a brown glass, with a flow-structure slightly indicated by small 



1 See G-eol. Mag. 1888, p. 418. 



2 See Mayer-Eymar in K. A. von Zittel's ' Beitriige zur Geol. u. Palaeont. 

 der Libyschen Wuste, &c.' Palaeontographica, vol. xxx (1883) pi. xxiii. 



3 I have been \inable to identify three localities from which specimens were 

 brought by Lord Lovat, but the rocks, like those of Mount Yoel (Yoil). were 

 mainly basalts. 



