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alters the appearance ; at the distal end, I can detect only one of the small teeth, of which 2 

 are usually found in Neritidae and Ncritopsidae. The tooth corresponding to the mushroomlike 

 teeth of the last named families, (5,2) has an erect position, quite different from the horizontal 

 position in Neritidae, its basal part is triangular, with the shortest margin below, the reflected 

 margin is provided with about 15 small denticles; the uncini (5, U) are very numerous, each with 

 about 8 denticles ; the arrangement of the teeth on the radula, resembles that of Hydrocena. This 

 radula agrees with that of Ncritopsis, by its wanting the rhachidian tooth, but otherwise it is 

 quite different; from the Neritidae it differs by the same character and by the shape and number 

 of teeth. Its place may be near some genus of operculate landshells. How far the other species, 

 located by v. Martens in Neritilia, agree in structure of the radula, must be made out by further 

 researches, especially of those species, without an appendix at the operculum. I think, Neritilia 

 has as much or even more right to stand as a separate family than Ncritopsis. As the family 

 characters are the same as those of the subgenus as defined by v. Martens, I have not repeated them. 



Neritilia v. Martens. 



1 . Neritilia rubida Pease. 



PEASE. Proc. Zool. Soc. Lond. 1865, p. 514. 



American Journ. of Conch. III, p. 285, PI. 24, fig. 5. 



V. Martens. Martini-Chemn. Conch. Cab. Ed. II, Neritina, p. 244. PI. 23, fig. 19, 20. 



Stat. 115. Kwandang, North Celebes, river. 11 Spec. 

 Stat. 142. Obi Major, river. 8 Spec. 



This species is the second Neritilia from Celebes, the first from Obi. It was only known 

 from the Pacific, where it lives on several Polynesian isles. I at first thought, it might be a 

 new species, as I found the spire rather blunt, the pillar lip not quite flat, and observed more- 

 over a small sharp angle at the basal part of the aperture, near the junction of the outer and 

 basal margins ; this seems to be a character of the group, not yet observed by authors, I find 

 the same angle in N. succinea Recl. from Guadeloupe and in N. Manoeli Dohrn from West 

 Africa. Opposed to the assertion of v. Martens, I see also a very small list, behind the lower 

 muscle-scar, inside the aperture, but I find the same in the specimen of N. rubida Pse, received 

 from v. Martens. So it seems to have escaped his attention. I have convinced myself, by means 

 of the point of a needie, that it is truly a convexity and 110 optical illusion, as is sometimes 

 the case, for instance in some Trochidac. 



Septaria Férussac. 



1 . Septaria stiborbiailaris Sowerby. 



Sowerby. Cat. of Shells Earl of Tankerv. Appendix p. 10, N" 1092. 



RUMPH. Amb. Rariteitkamer, p. 123, PI. 40, fig. O. 



v. Martens. Martini-Chemn. Conch. Cab. Ed. II, Navicella, p. 31, PI. 6, fig. 5 — 14. 



Webcr, Zool. Ergebn. Band IV, Süss- u. Brackw. Moll. p. 84. 



Stat. 33. Bay of Pidjot, Lombok. River. 7 Spec. 



Stat. 50. River near Labuan Badjo. 1 Spec. 



Stat. 180. North coast of Pulu Kelang. River. 8 Spec. . 



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