598 Bulletin American Museum of Natural History [Vol. LITT 
Cleopatra, Viviparus, Pseudavicula, and Mutela, lives on the oozy bottom 
of the open lake, the bivalves being buried deep in the mud. In. some 
places dead shells of these species form important deposits. 
Lake Bangweolo 
Lake Bangweolo (or Bangweulu, called by the natives “‘Bemba’’) 
lies in about 30°S., between 10° 40’ and 11° 30’ E., at an altitude of 1,140 
m. It covers about 3,000 square kilometers and occupies an extremely 
shallow basin bordered on all sides by low shores. The eastern and 
southern parts especially, where it receives the Chambezi and other 
small tributaries and where it flows out into the Luapula, are little more 
than an extensive morass of reeds and papyrus, divided by many channels 
into muddy, partly floating islands. Only on the western side are the 
banks clearly defined. The greatest extent of open water is not more 
than 100 kilometers long from north to south and hardly 40 kilometers 
wide from east to west. Even inthis open portion the lake is nowhere 
over 5 m. deep. The water is apparently quite fresh. A considerable 
amount of alluvial’ matter is steadily carried into the basin, while the 
Luapula slowly drains more of the water as it erodes a deeper channel 
through the various stretches of rocky barriers that interrupt its upper 
course. The gradual silting up and disappearance of Lake Bangweolo is 
therefore steadily progressing.! 
We were unable to find much information concerning the fauna 
of this lake. Weatherley? has reported that it is absolutely shell-less, © 
but it seems difficult to believe that such is actually the case. The region 
_ appears never to have been visited by a malacologist. 
Notes on the Relations of the Ethiopian to Other Regions 
The isolation of the Ethiopian Region from the Palearctic appears to 
have been of long standing, since the European Tertiaries, rich in land 
and fresh-water shells from the Paleocene to the Pliocene, appear about 
as free from Ethiopian forms as the modern European fauna. The char- 
acteristically Palearctic genera now found in the Ethiopian Region 
(such as Pupillide, Lymnxa, Vi'rina) probably came by way of Asia. 
Chapin believes that ‘‘in Miocene time there was a belt of tropical rain 
forest stretching most of the way between India and Africa,” and such a 
tRecent accounts of physical conditions in the Lake Bangweolo area are to be found in: 
Rosen, E. von. 1916. ‘Traskfolket.’ (Stockholm), 468 pp., 3 Maps, 78 Pls. 
Fries, R. E. 1921. Wissenschaftliche Ergebnisse der schwedischen Rhodesia-Kongo-Expedition 
sige 8 Leitung von Eric Graf von Rosen. I. Botanische Forschungen.’ Erginzungsheft, 
pp., Eis 
2Weatherley, P. 1898, ‘Circumnavigation of Lake B : 
pp. 241-209, Map, gation of Lake Bangweolo.’ Geograph. Journ. London, XII, 
