1927] _ Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 243 
Species of Syncera Recorded from the Belgian Congo 
Syncera hesset (O. Bosttger) 
Assiminea (Huassiminea) hessei O. Barrarr, 1887, Jahrb. Deutsch. Malakoz. 
Ges.,° ATV, py 180, PI vi, fig. 7. C. KR. Barter. 1914. Aan: Soc. Boal, 
Malacol. Belgique, XLVII, (1912), p. 106. , 
~-- Banana, abundant in swamps behind the English trade house (type locality : 
P. Hesse Coll.). . 
beta Valvatide 
Shell small, thin, turbinate to discoidal, openly umbilicate, composed of few, 
tubular whorls. Aperture circular, subvertical; peristome thin, continucus. Oper- 
culum very thin, corneous, orbicular, multispiral, composed of many narrow whorls; 
the nucleus central. 
Animal said to be hermaphroditic.. Foot lyre-shaped. Proboscis rather long. 
Eyes sessile at the inner bases of the slender tentacles, which are blunt at the tips. 
The gill is symmetrically bipinnate, attached at the base only, and capable of exten- 
sion forward, out of the branchial cavity. There is a tentacle-shaped appendage on 
the mantle-edge and a long penis at the right side of the neck. The teeth of the radula 
have finely serrate cusps, the central tooth being broad, without basal tentacles. ° 
The nervous system is orthoneurous. 
The only known genus, Valvata O. F. Miller (1774, ‘Verm. Terr. 
Fluv. Hist.,’ II, p. 198. Monotype: Valvata cristata O. F. Miiller), 
is generally distributed in the northern hemisphere extending into 
Northern Africa and Egypt. We have not. seen the following three 
species, described from the northern half of the Ethiopian Region; 
they appear to be true representatives of this genus. 
Valvata revoili BouRGUIGNAT, 1889, ‘Moll. Afrique Equator.,’ p. 189, Pl. viz, 
figs. 5-6. Webi River, above Guelidi, Somaliland. 
Valvata scioana (Pollonera) = Valvata nilotica var. scioana POLLONERA, 1888, 
Bull. Soc. Malacol. Italiana, XIII, p. 82. Cimbisi near Debra-Braham, Choa District, 
Abyssinia. 3 
Valvata tilhot GeRMAIN, 1909, Bull. Mus. Hist. Nat. Paris, p. 376; 1911, ‘Doc. 
Scientif. Miss. Tilho,’ II, p. 207, Pl. 11, figs. 26-31. Eguei district, east of Lake Chad. 
Littorinide (?) 
PSEUDOGIBBULA Dautzenberg 
. Pseudogibbula DauTzENBERG, 1891, Bull. Ac. Sci. Belgique, (3) XX, (1890), 
p. 570. Monotype: Pseudogibbula duponte Dautzenberg. | 
Shell imperforate, rather thin, conoidal, with obtuse summit, almost always 
eroded. Spire of three to four feebly convex whorls, with well-marked sutures; the 
whorls somewhat flattened above, the last bi-angulose and slightly concave at its 
base in the umbilical region. Surface covered with numerous spiral cords alternately 
heavy and feeble; on the penultimate whorl one counts about ten heavy ones. Fine 
and arcuate growth-strie render the ribs somewhat granulose. Aperture rhomboidal. | 
Outer lip simple, acute, smooth and shining; but not nacreous inside. Columella 
feebly arcuate, oblique, toward its base with a denticulation due to the termination 
