244 Bulletin American Museum of Natural History [Vol. LITI 
of a spiral funiculus which enters the shell (or sometimes this is lacking). Callosity 
of the columella depressed, very shiny, distinctly limited and connected with the outer 
lip through a very thin, shiny deposit. Color uniformly dark chestnut-brown except 
for the white columella. Operculum corneous, thin, paucispiral, with lateral nucleus, 
pale yellowish brown. 
According to Dautzenberg this curious snail belongs to the family 
Littorinidse. The shell certainly resembles Littorina more than it does 
any amnicolid snail, but as the soft parts and radula are unknown, its 
place in classification is uncertain. 3 
a b 
Fig. 40. a-b, Pseudogibbula duponti Dautzenberg. Two of the original lot. 
Pseudogibbula duponti Dautzenberg 
Text Figure 40a-b 
Pseudogibbult dupontt DauTzEnBERG, 1891, Bull. Ac. Sci. Belgique, (3) XX, 
(1890), p. 570, Pl: 1, figs. 2-6. 
_ Type locality: this species was found in eae numbers at Vivi (opposite Matadi), 
“sur des roches de gneiss amphibolique qui émergent sur le bords des rapides du 
Congo 4 l’époque des basses eaux, maisuiq sont constamment mouillées par les remous 
produits par les tourbillons.” (E. Dupont Coll.). The locality is about 125 kilo- 
meters above the mouth of the Congo, at the upper edge of the estuary. Itis therefore 
considerably removed from the influence of brackish water, since the tides are not, 
much perceptible beyond Boma, some 50 kilometers fines downstream. 
The specimens figured, which we owe to the kindness of Dr. H. 
Schouteden, are part of the original lot. They confirm Dautzenberg’ Ss 
characterization, translated above, except that one specimen lacks the 
prominence of the columella, which is simply concave. 
Cerithiide 
Shell usually turriculate, many-whorled, often very large; frequently varicose, 
tuberculate, spinose, or costulate. Aperture with the outer lip expanded, often con- 
siderably so; with a notch or sinus near the upper insertion and with a broad, more or 
less twisted channel below. Operculum corneous, spiral, with central or sublateral 
nucleus. . 
