's RIJKS MUSEUM VAN NATUURLIJKE HISTORIE — LE IDEN. 17 



The specimens are too young for identification without doubt, they 

 agree in most respects with the description, but the auricles are not 

 sufficiently developed, probably on account of youth. 



2. Neritina (Hemisphaericae) canalis Sowerby. 



Sowerby. Cat. Tankerv., App. 9. v. Martens. Martini-Chemn. Conch. Cab. 

 Ed. II, Mon. Neritina, p. 47, PI. 1, fig. 10-13. 



Mbai-river, near the mouth, May 3, 1910. 



The soft parts and operculum, were in a tube with those parts of N. 

 communis, while the only shell of canalis was in a box of shells of N. 

 communis, as these soft parts belong, without doubt, to a species of the 

 group under consideration, I have united them in one and the same tube. 



3. Neritina (Pictae) variegata Lesson. 



Lesson. Voy. Coquille, Zool. Vol. II, p. 378. v. Martens. Martini-Chemn. Conch. 

 Cab. Ed. II, Mon. Neritina, p. 98, PL 10, fig. 11—17. v. Martens, Siiss. u. 

 Brackw.-Moll. des Ind. Arch. p. 78. Tapp. Canefri. Fauna Mai. N. Guinea, p. 64. 



Region of the Mbai-river, branch of the Mbai-river near Hollandia, 

 May 6, 1910. 



The specimen collected near Hollandia is very small, but has already 

 the orange-red spot on the columellar plane, so characteristic for this 

 species, on the other specimens it is very well developed. 



4. Neritina (Pictae) communis Quoy & Gaimard. 



Quoy & Gaimard. Voy. Astrolabe, Zool. Vol. Ill, p. 195, PI. 65, fig. 12—14. 

 v. Martens. Martini-Chemn. Conch. Cab. Ed. II, Mon. Neritina, p. 113, PI. 11, 

 fig. 1 — 9. v. Martens. Siiss- u. Brackw.-Moll. d. Ind. Arch. p. 79. Tapp. Canefri. 

 Fauna Mai. N. Guinea, p. 68. 



Mbai-river, near the mouth, May 3, 1910; Faté-river, near the mouth. 



The numerous specimens from the Mbai-river have broad, black 

 streaks, often much crowded, that from the Faté-river is still young and 

 has the same markings. 



5. Neritina (Neritodnjas) cornea Linné. 



Linné. Syst. Nat. Ed. X, p. 777. v. Martens. Martini-Chemn. Conch. Cab. Ed. 

 II, Mon. Neritina, p. 140, PI. 12, fig. 14—18. Tapp. Canefri. Fauna Mal. N. 

 Guinea,, p. 70. 



Sëko, Aug. 2, 1911. 



One very characteristic specimen has been collected. 



(8-111— 191a-. 



