Vol. XI, Nos. 10 & 11.) The Fauna of the Jordan System. 461 
[N.S. 
Two elements are thus represented by the Cyrinidae, (a) 
an endemic Syrian element #7 pe a tropical one common 
Africa and the Oriental Regi 
Considering the molluscs of the Lake of Tiberias as a whole, 
we find, therefore, that the fauna is a composite one, mainly 
Palaearctic and including a large proportion of endemic Syrian 
species, but also containing a tropical element. No represen- 
tative of this tropical element is exclusively African, and, 
considered by itself, it would appear to be just as much 
ee as Ethiopian 
T s no genus or subgenus of molluscs endemic in 
the von system. The molluscan fauna of the Lake of 
Tiberias agrees well with that of other parts of the system, 
and more aeons with that of the northern section thereof, 
but it also includes a number of strictly local species, none 
of which are of a highly capuetaliael nature. 
Craniata. 
I have already dealt with the present distribution of the 
Fishes, Batrachia and Reptiles (Journ. As. Soc. Bengal (n.s). 
IX, pp. 31-41: 1913), and have nothing to add except to state 
that I was probably wrong in placing T'tlapia magdalenae in 
the genus Paratilapia. Boulenger, however, is of the @ opinion 
that Hemichromis sacra, Giinther, should be placed in that 
genus. I bow to his oreatly superior knowledge. 
III. ORIGIN OF THE FAUNA OF THE 
JORDAN SYSTEM. 
The most remarkable point in the distribution of the aquatic 
animals of the Jordan system is the fact that whereas there is un- 
mistakable Ethiopian element among the fishes, no such element 
can be detected with certainty among the invertebrates. This 
apparent anomaly can be discussed only in the od i the geo- 
logical history of Palestine and the neighbouring co ies 
in of the river Jordan has been adored an} 
ey. g ent geogra gi especially by Hull, 
- thaig! ae ee The Tank z uthor has codified and 
applied existing knowledge on the “subheok in a pace 
ces and interesting manner, and there seems to be 
ee = Palestine 
td the Geo Yy ad Doosrably a diebia P etraea, s 
ete., * Manoir om sete Conditions of the Mediterranean Basin, 
Trans. Vict. I: 5. 
™ ‘The Bane of the Bart h, Eng. Ed. I, pl. ao gt chap. IX, 1906. 
5 The Great Rift Valley, Chap. XIII, 
