1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 597 
Many of the Mollusca known from the lake were examined by 
us.! They total 20 forms (13 Gastropoda and 7 Pelecypoda), oe to 
14 genera: 
Lymnxa natalensis (perhaps subsp. un- ,*Melanoides mweruensis 
dussume) *Cleopatra johnstoni 
Planorbis adowensis Sor Ae MWErUuensts 
Physopsis africana globosa Corbicula radiata 
Burnupia sp. (recorded as stuhlmanni) Parreysta mweruensis 
Lanistes ovum | *Pseudavicula johnstoni 
*Viviparus crawshayt *Mutela hargerz 
«3 . MWETUeNsts oo Corres 
» . de var. pagodiformis Aspatharia sp. (undescribed) 
* Melanoides crawshayt | Etheria elliptica 
Hf eg: ematatrix | 
Of these twenty forms, ten may be regarded as endemic and were 
marked as such in the above list. It should, however, be noted that 
five of them, viz. Melanoides crawshayi, M. mweruensis, Cleopatra john- 
stom, Pseudavicula johnston, and Mutela hargeri, are not absolutely 
restricted to the lake proper, but extend into the lower reaches of the 
Luapula, below the Johnston Falls, where the river becomes shallow 
and sluggish. All of these mollusks are evidently related to the usual — 
Ethiopian fresh-water types. Yet in some cases they have acquired a 
peculiar shape or sculpture, and this, added to their great abundance, 
lends to the fauna a facies quite its own. This is especially true of the 
heavy and strongly keeled Viwiparus mweruensis, which some authors 
have even transferred to Neothawma; but we do not believe that it has any — 
real relationship to that Tanganyikan genus. The curiously bialate 
unionid Pseudavicula johnstoni has been separated as a distinct genus, 
endemic in Moero, from the other African members of the family; it 
reminds one somewhat of the Tanganyikan Pseudospatha, but it lacks 
the bright periostracum and iridescent nacre of that genus. Mudtela 
hargert is equally remarkable among the Mutelide. | 
Lymnzxa, Planorbis, and Physopsis inhabit the pools at or near the 
shore, together with a species of Succinea (S. baumanni, according to 
Dautzenberg and Germain) that crawls over the amphibious plants above 
the surface of the water. Lanistes is mostly found in the swamps 
of the southern coast. The junior author collected Burnupia 
from’the under side of floating leaves of water-lilies in the bay of Kilwa. 
The typical Moero fauna, however, such as the species of Melanovdes, 
~ 1The junior author collected a number of them in December, 1911 and January, 1912. 
