KEPORT ON THE GASTEROPODA. 451 



Natica Cliemnitzii, Angas, Port Jackson Moll., Proc. Zool. Soc. Lond., 1867, p. 198, No. 70. 

 „ Lamarckiana, Lischke, Jap. Meer. Conch., vol. i. p. 80. 

 „ didyma, Brazier, " Chevert " Exped. Mar. Shells, Proc. Linn. Soc. New South Wales, 1877, 



vol. i. p. 238, No. 59. 

 „ Cliemnitzii, v. Martens, Moll. Mauritius, &c, p. 276. 

 „ didyma, Sowerby, Thes. Conch., pts. 39, 40, p. 77, sp. 7, pi. ccccliv. (i. Gen.), fig. 4. 



April 17-18, 1874. Port Jackson, Sydney. 2 to 10 fathoms. 



Habitat. — The whole Indian Ocean, in particular Madagascar, Ceylon, Nicobar Islands, 

 Malay Archipelago, Australia (v. Martens) ; Bay of Bengal and " Hinterindien " (Philippi) ; 

 New Guinea (Brazier) ; Sydney (Augas) ; Japan (Lischke). 



At first sight the specific distinctness of the forms here classed as one species seems to receive 

 strong support from the fact that both Philippi and Eeeve have made four' species of them, but in 

 point of fact the numerical agreement is all that these two authors present, for it is impossible to 

 correlate their species. Possibly the Natica cliemnitzii, Reel., is equal to Natica didyma, Bolten, and 

 with more probability Natica petiveriana, Reel., equals Natica papyracea, Von der Busch ; but beyond 

 that one can only guess, and after very full and patient examination of the different species and compari- 

 son of all the descriptions in Reeve and Philippi, Mr Edgar Smith and I were decidedly of opinion 

 that, as indicated above, they must be united. These conclusions will be best shown by adding here 

 a note with which Mr Smith has kindly favoured me as the result of our study. 1 



24. Natica (Mamma) aurantia, Lamarck. 



Chemnitz, Conch. Cab., vol. v. p. 283, pL clxxxix. figs. 1934, 1935. 

 Natica aurantia, Lamarck, Anim. s. vert., vol. vi. (2) p. 198, and (ed. Desh.) vol. viii. p. 632, sp. 6. 

 ,, „ Deshayes, Encycl. method., vers, vol. iii. p. 599, sp. 6. 



„ ,, var. strami7iea, Recluz, Proc. Zool. Soc. Lond., 1843, p. 211. 



1 "Natica (Neverita) didyma, Bolten. 



Natica didyma, Bolten ; Philippi, Krister's Conch. Cab., p. 6, pi. i. figs. 1-4. 



,, ampla, Philippi, Zeitschrift Malak., 1848, p. 156, and Kiister's Conch. Cab., p. 41, pi. vi. fig. 2. 

 „ papyracea, Von der Busch ; Philippi, Abbildungen, vol. ii. pi. ii. fig. 14 (junior). 

 „ lamarckiana, Recluz MS., Reeve, Conch. Icon., vol. ix. pi. ii. fig. 6. 

 var. = Natica bicolor, Philippi, Kiister's Conch. Cab., p. 43, pi. vi. fig. 4. 

 „ = Natica petiveriana, Recluz MS. , Reeve, toe. cit., sp. 1 7. 

 „ = Natica cliemnitzii, Recluz MS., Reeve, loc. cit, sp. 7. 

 „ = Natica problematica, Reeve, loc. cit., sp. 21. 

 ,, = Natica intermedia, Recluz, not of Philippi. 

 „ = Natica incisa, Dunker, Philippi in Kiister's Conch. Cab., p. 81, pi. xii. fig. 8. 



Habitat. — Gulf of Yedo. Also Philippines, China, North Australia, and New South Wales. 



This species varies considerably in form and the extent of the umbilical callosity, which, however, displays 

 a quite constant peculiarity in being subdivided by a more or less deeply transverse furrow. The umbilicus, 

 too, is much more open in the typical form than in the var. named by Recluz Natica cliemnitzii, but these 

 differences are mainly individual, for in a series of forty-two specimens in the Museum, it appears impossible to 

 draw a line of demarcation around any of the so-called species. Colour also is of no assistance, the chief variation 

 consisting in the intensity of the tint of the aperture and the whiteness of the base." 



