1927] Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo 149 
dating from Westerlund, it may take as type A. lacustris (Linnzus), 
since this is the type of Ate of which genus Westerlund considered 
“Helicon” to be a synonym. 
“Calytra”’ was likely an error for Calyptra Klein, 1753 (‘Tentamen 
Methodi Ostracologice,’ II, p. 118). Klein’s work was prior to the 
foundation of the binominal system of nomenclature (1758). It may 
be disregarded in the selection of a type for the new name Calytra Wester- 
lund. As the latter was introduced as a synonym of Ancylus, A. lacus- | 
tris (Linneeus) is to be taken as the type. 
Both of these names will thus become synonyms of Ancylus O. F. 
Miller, having the same genotype. 
Ferrissiinse Walker 
Shell patelliform, the apex more or less turned to the right, and finely radially 
striate, punctate or smooth. 
Radula with a bicuspid central, the base more or less wider below; laterals and 
marginals obliquely reflected above, with from three to five cusps owing to the 
splitting up of the mesocone and ectocone, which do not usually extend below the 
basal. 
FerRissia Walker 
Ferrissia WALKER, 1903, The Nautilus, XVII, p. 15, as a section of Ancylus. 
Type by original designation: Ancylus rivularis Say. 
Apex minutely radially striate, the rest of the shell smooth or radially striate; 
the aperture not contracted by a partition or deck at any stage. 
Bryant Walker gives the distribution as “‘ world-wide, but lacking in 
Europe and apparently in Siberia, Syria, and the south shore of the 
Mediterranean (excepting in the Nile Valley, and a single, possibly 
adventitious species in Algeria), Madeira and the Canary Islands; 
apparently also wanting in Mexico, Central and South America.”’ 
The following species of Ferrissia are known from the Ethiopian 
Region. 
Ferrissia burnupi B. WALKER, 1924, ‘Ancylide of South Africa,’ p. 67, fig. 28 
(on p. 69); Pl. 11, fig. 23=Ancylus (Ferrissia) burnupt B. WauKER, 1912, The 
Nautilus, XXV, p. 142. Equeefa River, Natal. Elsewhere in Natal and Transvaal. 
Ferrissia cawstont B. WALKER, 1924, ‘Ancylide of South Africa,’ p. 70, Pl. 11, 
figs. 25-26. Mooi River, Potchefstroom, raneenal: Elsewhere in ‘Eaarvaall This 
species was mentioned as Ancylus cawstoni “ ‘Burnup” by Cawston (1918, Parasit- 
ology, XI, p. 94). 
Ferrissia chudeaui GERMAIN, 1917, Bull..Mus. Hist. Nat. Paris, p. 526, figs. 12-14 
(on p. 526) and 15-17 (on p. 527). Bakoy River at Tukoto, Senegambia. 
1Patella lacustris Linnseus was designated as the type of Ancylus Miller by Children, 1823, ‘La- 
marck’s Genera of Shells,’ p. 95. 
