556 PROCEEDINGS OF THE ACADEMY OF [DeC, 



1846-1858. Natica chemnitzii Recluz, in Chenu, Illustrations Con- 

 chyliologiques, Vol. Ill, pi. 3, fig. 4. Reeve, Conchologia Icon- 

 ica, IX, 1855, pi. 2, fig. 7 (not of PfeifTer, 1840). 



1852. Natica incisa ''Diinker," Philippi, Conchylien Cabinet, Natica, 

 p. 81, pi. 12, fig. 8 (China). 



1852. Natica papyracea Busch, var. major Philippi, Conchylien Cabi- 

 net, p. 157, pi. 5, fig. 4. 



1855. Natica lamarckiana "Recluz," Reeve, Conchologia Iconica, 

 IX, pi. 2, fig. 6. 



1855. Natica prohlematica Reeve, Conchologia Iconica, IX, pi. 6, 

 fig. 21. 



1860. Natica rohusta Dunker, Malakozoologische Blatter, Vol. ^^I, 

 p. 232; Mollusca Japonica, 1861, pi. 2, fig. 24 (Deshima). 



1876. Natica tasmanica Tenison- Woods, Papers and Proceedings 

 and Report of the Royal Society of Tasmania, 1875 (1876), pp. 

 148, 149; 1877 (1878), p. 32; 1890 (1891), p. 134, species 173. 

 Proceedings Royal Society of Victoria, Vol. XII, 1900, p. 192. 

 Polinices tasmanica T. Woods, Tate and May, Proceedings Lin- 

 nean Society of New South Wales, Vol. XXVI, No. 103, 1901, p. 

 375, pi. 25, fig. 49. 



The study of a series of 53 specimens in 23 lots, from localities in 

 Japan, China, India, the East Indies and Australia, shows that sev- 

 eral species and races can be distinguished, as follows: 

 Polinices didyma Bolten. PL XXIX, fig. 9. 



Size rather large, up to 59 mm. diam. Coloration as in didyma 

 ampla Phil., from which it differe by the subtriangular shape of the 

 umbilical callus, which has a long adnate upper border and less pro- 

 jecting outer edge than P. didyma ampla Phil. 



Type locality, Tranquebar. Bolten's species was based on Chem- 

 nitz's figures. We have seen no examples from Tranquebar, but the 

 figures seem to show no tangible difference between didyma and the 

 common Japanese species described as N. rohusta Dkr., which we 

 consider a synonym, pending the comparison of topotypes. We have 

 rohusta from Tashima, Awaji (Hirase), and Hayama, near Kamakura, 

 Sagami (Miss Hartshorne). It seems to be confined to Japan and 

 India. 



Fig. 9 of plate XXIX represents a Japanese shell. 

 Polinices didyma ampla Phil. PL XXIX, fig. 8. 



A large form, ordinarily attaining the diameter of 63 mm. The 

 umbilicus is very ample, the excavation not half covered by the callus. 



