1927] Pilsbry-Bequaert, The Aquatic M ollusks of the Belgian Congo ~—- 165 
Theodoxia BOURGUIGNAT, 1877 Bull. Soe. Sci. Phys. Nat. Toulouse, III, (1875- 
76), p. 92. Emendation of Theodozus. 
Neritina section Theodorus Pauuary, 1923, Archives Inst. Pasteur Afr. du N ord, 
III, p. 44. Misspelling of Theodoxus. 
Agrees with Neritina in characters of shell and operculum. 
Radula: inner lateral less than twice as broad as long, its posterior lobe large, 
usually rounded, with convex outer slope; reflection of the outermost lateral well 
developed, honine and with a tendency to increase the inner point so as to be broadly 
lanceolate in shape; blades of inner marginals with serrations on outer side. 
The species are estuarine or fluviatile and found over much of the 
Old World, not in America. 
Baker’s examination of the radula of Neritina afra Goves has 
shown that this species is a Theodoxus. It has been placed in the section 
Vittoclithon H. B. Baker (1923, Proc. Ac. Nat. Sci. Philadelphia, LX XV, 
pp. 134 and 156; type: Neritina meleagris Lamarck) of the subgenus 
Clithon Denys de Montfort (1810, ‘Conchyl. Systémat.,’ II, pp. oan and 
327; type: Nerita corona Linnzeus). 
Theodoxus afer (Sowerby) H. B. Baker, 19238, Proc. Ac. Nat. Sci. Philadelphia, 
LXXV, p. 158, Pl. x1v, fig. 26 (radula) = Neritina afra SowERBy, 1843, ‘Conchol. 
[llustrat.,’ Neritina, fig. 13 (p. 3 of explanation). Neritina equinoxialis MoRELET, 
1848, Rev. Zoolog. Soc. Cuviér., p. 355, and 1858, ‘Séries Conchyl.,’ I, p. 29, Pl. 11, 
fig. 6. Fernando Po and Prince’s Island. 
Neritiliinze 
Operculum without peg, but with an erect, marginal projection representing the 
rib. Shell globose. 
Eyes pedunculate. Radula: unpaired central absent; inner laterals with long 
axes almost parallel to that of the radula, the inner ends alternating on opposite 
sides; of the two middle laterals the outermost is rather elongate; of the outer laterals 
the innermost is vestigial, the outermost is very oblique, with crescentic disk and well- 
marked cusps; marginals with large, crescentic, cusp-bearing disks and with promi- 
nent notch on the inner side near the distal end of the body. 
This subfamily contains only one genus, the few species of which are 
fluviatile and are found in the tropics of America, Africa, and the Pacific 
Islands. 
| Nerititia E.. v. Martens 
Nerttilia E. v. Martens, 1879, in Martini and Chemnitz, ‘Syst. Conch. Cab., 
IT, 10, Neritina,’ p. 19. Type: Neritina rubida Pease. 
The following Ethiopian species is apparently a true Neritzlza. 
Its radula has, however, not yet been studied. 
Neritilia manoéli (H. Dohrn) =Neritina manoéli H. Dourn, 1866, Malakoz. 
Blatter, XIII, p. 135. HE. v. Marrens, 1879, in Martini and Chemnitz, ‘Syst. Conch. 
Cab., II, 10, Neritina,’ p. 244, Pl. xxit1, figs. 21-22. Tryon, 1888, ‘Manual of 
Conchol.,’ X, p. 54, Pl. viru, fig. 87. Prince’s Island. 
