MOLLUSCA. 
223 
common European freshwater sliells as oceurring also in Al- 
geria : — Neritina Jlnviatilis ; Pisidium amnicum, casertammi^ pu- 
sillum,, nitidmn ; Unto litoralis, hatavm, pictorum. Most Algerian 
species of land- as well as of freshwater shells are either identi- 
cal with or nearly allied to those of Spain. Lists of the species of 
Tunis, Morocco, Canary Islands, Madeira, Sicily, and Spain are 
given to prove the near relation of the North African to the 
Spanish fauna and its differences from that of the neighbouring 
islands mentioned. The littoral Mediterranean land-shells are 
found in Algeria, not only on the sea-coast, but also on the 
northern borders of the great desert, south of the secohd moun- 
tainous mass of the Atlas, and in the vicinity of some former 
salt lakes. In the same manner the fauna of the mountainous 
region, which consists chiefly of flattened earinated land-shells, 
occurs again on the southern slope of the central elevated plains, 
which are distinguished by a peculiar fauna, the shells being 
very thick and most of the terrestrial species having a toothed 
aperture. The author comes to the conclusion that Morocco, 
Algeria, and Tunis were, at the beginning of the present 
geological period, a peninsula connected with Spain at Gi- 
braltar, separated by a sea (now the desert of Sahara) from the 
rest of Africa, by the Mediterranean from Sicily and Italy, and 
by the Atlantic from the Canary Islands and Madeira. 
The geographical configuration of that period is represented 
on a map. 
Martens, E. v. Uebersicht der Ijand- und Siisswasser-Mol- 
lusken des Nil-Gebietes. [Synopsis of the land- and fresh- 
water shells of the Nile countries.] Mai. Blatt. xii. pp. 
177-207. Contains the land-shells and the Ctenobranchiates, 
the continuation being published in the following volume 
(1866, pp. 1 et seq). 
A small collection made by the author at Kairo and Alex- 
andria, another by Dr. Robert Hartmann during his travels in 
the Sennaar, Nubia, and Egypt, and that made some forty years 
ago by Ehrenberg are the materials for this paper. A short 
history is given of our knowledge of this fauna, from Hasselquist 
and Eorskal to the present time, and special attention has been 
paid to the synonymy, as even some of the m ost common and best- 
known Nilotic species have been repeatedly described as new — 
for instance, Paludina huJhnoidcs (Olivier) as Melania fpgyptiaca 
(Reeve) . Eight species of Helix are pointed out as erroneously 
enumerated in the Egyptian fauna by various authors. Lower 
Egypt (the land-shell fauna of which does not differ from that of 
the coasts of the Mediterranean), Middle and Upper Egypt, the 
desert parts of Nubia, Abyssinia, and the wooded countries of the 
White and Blue Nile are indicated as principal divisions of this 
fauna. With regard to land-shells, there are very striking dif- 
