OF THE HALOLIMNIC FAUNA OF LAKE TANGANYIKA. 315 



Egypt might be included in this district, where, as in the 

 case of the Nubian sandstone, beds of Cretaceous age rest on 

 the Archaean. Altogether the Cretaceous and Tertiary beds of 

 this region are analogous to those of Syria and of countries still 

 further to the eastward. The southern extension of the great 

 Cretaceous overlap in this area is not exactly known ; but 

 De Lapparent* has recently announced the discovery of Eocene 

 fossils on the frontier of Sokoto due west of Lake Tchad. He 

 also announces the discovery of an upper Cretaceous echinoid, 

 believed to be from Belina, which is 300 miles north of the 

 same lake. 



The full significance of these discoveries can only be realised 

 by the aid of a map ; but among the results thus obtained we 

 find that marine deposits of Mesozoic and Tertiary age, as proved 

 by their fossils, are now^ known to exist within 1 4° north of 

 the Equator. Indeed there is no reason why a considerable 

 portion of the basin of Lake Tchad should not be underlain by 

 Cretaceo-Eocene formations, which in all probability extend 

 from the Atlantic coast of Senegal to the crystalline rocks of 

 the Ethiopian Highlands. The effect of this would be that a 

 much larger portion of Northern Africa than hitherto supposed 

 must be included in our second division, though the limits 

 between this and the third, or peninsular division, cannot yet 

 be defined. There is, however, one marked difference between 

 our second and third divisions, which cannot be too soon 

 realised, viz., that in the second division fossiliferous marine 

 beds of Mesozoic and Tertiary age penetrate into the heart of 

 the continent, whereas in the third division such beds occupy 

 but a narrow fringe between the sea and the peninsular massif. 

 Thus, the physical liistory of the two regions is entirely 

 different. 



(3) Peninsular Africa. — Constitutes the third division, and 

 this may be divided as follows : — 



Section a. — The Cape Beds, which have now been studied for 

 a long time, and which it is necessary in some measure to refer 

 to, if we would endeavour to understand the geology of 

 Equatorial Africa. Thei'e is a useful summary of these beds 

 in a recent issue of the Geological Ma/jazine,'\ which I condense 

 as follows : — 



* Bull Soc. GeoL France (4) III, No. 3, p. 299 (1903). 

 t December, 1903, p. 569. See also Seward, op. cit., November, 1903, 

 who deduces the age from plant evidence. 



