1927] Pulsbry-Bequaert; The Aquatic Mollusks of the Belgian Congo 587 
upon a critical examination of the synonymy as adopted in the taxonomic 
part of this work, the number of forms that may claim recognition as 
species, races, or varieties runs to 155 (109 Gastropoda and 46 Pelecy- 
poda), of which 143 are endemic (97 Gastropoda and 46 Pelecypoda). 
Although the lists given below certainly include names that eventually 
will be eliminated, we believe that these losses will be amply made up by 
new discoveries. The rather high figures might easily convey the im- 
pression that the malacological fauna of Tanganyika is now prefectly 
well investigated; but nothing would be farther from the truth, for, even 
in the small material we have studied, we have recognized several forms 
that had escaped our predecessors. 
The Mollusca of Tanganyika are readily distributed among three 
groups, based upon the degree of relationship to the usual fresh-water 
types. : 
(1) The first group comprises forms belonging to the usual fluviatile 
genera, also found elsewhere in African fresh waters. 
Lymnexa natalensis *Melanoides admirabilis 
aha catllaudt var. jouberts *Cleopatra guillemei 
Pe gravierr Ae jouberts 
Planorbis adowensis ye ate trisulcata 
“i bridouxianus sib eed ie var. foar 
RS dae fe var. foar *Corbicula tanganyicensis 
pita ps lavigerianus eee foar 
sudanicus tanganikanus *Pisidium hermosum 
anes moncetr Pats giraudr 
ed lamy2 *Parreysia horer 
Segmentina angusta Wis eae UJUJVENSIS 
*Planorbula tanganyicensis *Celatura gerrardt 
*Bulinus coulboist tear (?) béhma 
*  — randabeli date: calathus 
a calaris ee: charbonnieri 
*Physopsis tanganyicex paces, gerete 
*Ancylus tanganyicensis ee randabela 
Pila ovata * A spatharia anceyt 
ae ‘f var. bridour sea: lavigerrana 
Lanistes ellopticus * Muitela lavigertana 
+ Nouber FOU Once 
‘  bourguignats * ‘€  nilotica var. moines 
Viviparus unicolor eo  Bobenisormis ‘ 
io costulatus *Tridina speka 
petri SOG * “ — bourguignati — 
tas (?) brincatianus ieee evn ti 
is “var, bridounmi-  * “* landeaur 
* 
anus oe < pypekes 
Melanoides tuberculata 
anne Unr enn nian Bina OM UTS PESTER ESS LEA Le ee ee . e 
1As in other similar lists, the endemic forms are marked with an asterisk. 
