UNIO 727 
Type locality, Chozi River, a tributary of the Chambzi, flow- 
ing into Lake Bangweolo from the east. 
Unio choziensis Preston, Ann. Mag. Nat. Hist., (S), VI, 1910, 
p:-60,,pE iv, fig. 8. 
Unto GeRETI Preston, 
“Shell ovate, somewhat tumid, covered with a dark brown, 
silky periostracum and sculptured with fine, rather closely set, 
concentric lines of growth; umbones slightly eroded, prom- 
inent:; dorsal margin nearly straight; ventral margin scarcely 
rounded: anterior side angled above, obtusely rounded below ; 
posterior side sloping obliquely, sharply rounded below; lat- 
eral teeth short anteriorly, elongately curved posteriorly ; an- 
terior cardinal tooth in right valve short, rather square, erect, 
jagged, incised on the outer side; median cardinal tooth very 
small; posterior cardinal rather small, projecting; anterior 
cardinal in left valve bluntly triangular, incised posteriorly ; 
posterior cardinal bifurcate. thus presenting the appearance of 
a double tooth; anterior adductor scars ovate, well impressed ; 
posterior adductor scars moderately impressed; interior of 
shell pale bluish-white, somewhat iridescent. 
Length 36.5, lat. 61 mm.” (Preston). 
Type locality, Lake Tanganyika. 
Unio gereit Preston, Ann. Mag. Nat. Hist., (8), VI, 1910, p. 
Gi, pl. ty, feo. 
UNIO: SHIREENSIS Preston. 
“Shell ovate, moderately tumid, covered with a pale, reddish- 
brown, rather thin periostracum, which becomes thicker, fol- 
iaceous, and darker in color posteriorly, both valves sculptured 
with coarse, concentric growth-lines; umbones much eroded, 
very smal!; dorsal margin somewhat arched; ventral margin 
shghtly rounded; anterior side rounded above, sloping below ; 
posterior side bluntly rostrate ; anterior lateral teeth very short ; 
posterior laterals long and straight, slightly serrated; cardinal 
teeth curved, massive, jagged, especially in the left valve; an- 
terior adductor scar deeply excavated, squarish; posterior ad- 
ductor scar irregularly triangular, not deeply impressed; in- 
