Appendix II: Phytogeography and Geology. 1073 
course is the disappearance of the sandstone, sixty eight miles below 
the cataract, at Edfu, where the nummulitic limestone which forms 
the northern desert plateau, offers the stream an easier task in the 
erosion of its bed. It has thus produced a vast canon, cut across 
the eastern end of the Sahara to the northern sea. From cliff to 
cliff, the valley varies in width, from ten or twelve, to some thirty 
one miles. The floor of the cation is covered with black, alluvial 
‘deposits, through which the river winds northward. It cuts a deep 
channel through the alluvium, flowing with a speed of about three 
miles an hour; in width it only twice attains a maximum of eleven 
hundred yards. So far its course is the same as in old times, but 
a considerable change now takes place; for whereas formerly it 
discharged itself into the sea by seven mouths, at the present day 
these are reduced to two. The point of separation, which constitutes 
the apex at the Delta, has remained about the same. Its ancient 
name appears to have been Cercasorus, the modern representative 
of which may be placed at a point, opposite Shubra. Here the river 
anciently divided into three branches, the Pelusiac, running Kast, 
the Kanopicrunning West and the Sebennytic which flowed between 
these two, continuing in deed the general northward direction hitherto 
taken by the Nil and piercing the Delta through the centre. From 
this Sebennytic branch two others were derived, the Tunitic and the 
Mendesian, both of which emptied themselves between it and the 
Pelusiac branch. The lower parts of the remaining two branches, 
the Bolbitine and the Phatmitie, were artificial, and were constructed 
probably when the other outlets began to dry up. It is by these 
two mouths that the river at the present day finds its outlet. At 
the point of bifurcation the general direction of the two streams is 
probably that of the old Pelusiac and Kanopic branches, but they 
gradually quit the extreme EK. and W. course, and continue more 
in the centre of the Delta, the one to Damietta, and the other to 
Rosetta, from which places they derive their modern appellations. 
Phytogeographically Egypt belongs to the “North African-Indian- 
Desert Province”. The part on the western side of the Nile belongs 
to Engler’s?) “Province of the Great Sahara’, that on the eastern 
side of the Nile formed the “Egyptian-Arabian Province’. No more 
striking contrast can be imagined than that between the intensely 
cultivated Valley of the Nile and the barren deserts on either side. In 
citing the several localities for each species, it has appeared expe- 
dient to arrange them under five phytogeogravical regions, into which 
the large area embraced by this Flora has been divided?). These are: 
‘) Engler: Syllabus der Pflanzenfamilien, ed. VI (1909) p. 224. 
*) Ascherson-Schweinfurth: Illustration de la Flore d’Egypt (1887) p. 32. 
Muschler, Manual Flora of Egypt. 68 
