Suter. — Notes on New Zealand Mollusca. 325 



Ianthina ianthina, Linne (1758). 



Mr. Hedley kindly informed me that Linne bestowed the 

 above name on the species commonly known as /. fragilis, 

 Lamarck, 1801, and, having priority, should be used instead. 



Astralium sulcatum, Martyn, subsp. davisii, Stowe. 



Imperator davisii, Stowe, Trans. N.Z. Inst., vol. iv, 1872, p. 218. 

 Risella kielmannsegi, Zelebor, Verhandl. Zool. Bot. Gesellsch. 

 Wien, vol. xvi, 1866, p. 913 ; Reise der " Novara," Moll., 

 pi. i, fig. 11 ; Hutton, Cat. Mar. Moll. N.Z., 1873, p. 28 ; 

 Martens, Crit. List Moll. N.Z., 1873, p. 28. Risella aurata, 

 Hutton, Journ. de Conch., vol. xxvi, 1878, p. 27. Risella 

 melanostoma, Hutton, Man. N.Z. Moll, 1880, p. 79 ; Suter. 

 Trans. N.Z. Inst., vol. xxxiv, 1902, p. 215 ; Index Faunae 

 N.Z., 1904, p. 79. Astralium pyramidale, Webster, Trans. 

 N.Z. Inst., vol. xxxvii, 1905, p. 276, pi. ix, figs. 2, 2a. 



The prevailing tendency amongst conchologists to collect 

 only, as far as possible, adult specimens has led to the neglect 

 of the study of earlier stages of many of our shells. There is 

 no doubt that some of these young forms show characters 

 which in the adult are often more or less obliterated by corru- 

 gation, &c. Two instances are already mentioned in this paper 

 —viz., Turbo shandi and Turbo radina. The specimen described 

 by Zelebor was no doubt obtained in Auckland Harbour ; ex- 

 amples were also collected by Mr. T. F. Cheeseman, Rev. Mr. 

 Webster, and myself at Takapuna, but apparently all dead shells. 

 As far as I know the genus Risella is littoral, and it puzzled me 

 for a considerable time why our species should not be found 

 alive at Takapuna. The shells I found appeared to be young 

 forms only. Through the kindness of Mr. W. L. May I got a 

 number of Tasmanian young specimens of Risella melanostoma, 

 and on comparing these with our supposed Risella of the same 

 size I found the two decidedly distinct ; also, the R. kielmann- 

 segi recalls the habitus of R. melanostoma, as was already 

 pointed out by Zelebor. Some time back I found at Takapuna 

 and Narrow Neck young live shells of Astralium sulcatum, subsp. 

 davisii, and comparing these with the specimens of R. kielmann- 

 segi I found them to perfectly agree. Whenever a specimen 

 with the calcareous operculum was found it was thrown away 

 again, every conchologist recognising at once that it was only 

 a young Astralium, and they were never carefully compared 

 with the dead shells of the supposed Risella. 



The genus Risella has therefore to be omitted from the list 

 of New Zealand Mollusca. The Pliocene R. melanostoma, how- 

 ever, is undoubtedly that species, now extinct in New Zealand. 



