ORTMANN : TERTIARY INVERTEBRATES. 189 



Affinities: This species, as well as the closely allied N. moerickei v. 

 Ih. (=N. obtecta Moer.) from the Navidad beds, is characterized by the 

 umbilical callus, which is divided by a groove. Moericke has pointed out 

 that the most closely allied European form is the Oligocene N. hantoni- 

 ensis Sow. (see v. Koenen, 1867, p. 148, pi. 12, f. 9), and that other 

 related species are found in Cretaceous and Miocene beds of California. 

 The Californian Miocene species (N. callosa Gabb, 1869, p. 10, pi. 2, f. 17) 

 more resembles Moericke's form, while the European N. hantoniensis is 

 more like the Patagonian N. secunda. Since the California Cretaceous 

 species, N. secta and globosa, are a little more different in external form, 

 the closest relation of our species is with one of Oligocene age {N. han- 

 toniensis]. 



120. NATICA DARWINI Hutton. 



PI. XXXIII, Fig. 4. 



1846 N. solida Sowerby, in: Darwin, Geol. Observ. S. Amer., p. 255, pi. 



3, f. 40, 41 (non N. solida Blainville). 



1864 N. sol. Zittel, in: Novara Exp. Geol., p. 42, pi. 15, f. 6. 

 1873 N. sol. Hutton, Cat. Tert Moll. Echin. N. Zealand, p. 9. 



1885 N. sol. Hutton, in: Quart. Journ. Geol. Soc., v. 41, p. 550. 



1886 N. darwini Hutton, in: Tr. N. Zealand Instit., v. 18, p. 334. 



1887 N. sol. Philippi, Tert. & Quart. Verst. Chiles., p. 91, pi. 10, f. 10 

 (nee. fig. 1 8). 



1889 N. sol. Rochebrune & Mabille, in : Miss. Sci. Cap Horn, v. 6, p. 29. 



1896 N. sol. Moericke, in: N. Jahrb. Miner, etc., Bcil. Bd. 10, p. 558. 



1897 N. sol. v. Ihering, in: Rev. Mus. Paul., v. 2, p. 280. 



1899 N. darwini v. Ihering, in: N. Jahrb. Miner., etc., v. 2, p. 29. 



1900 N. darw. Ortmann, in: Amer. Journ. Sci., v. 10, p. 380. 



Shell subglobular, thick, smooth. Spire short, suture inconspicuous. 

 Umbilicus large, open, not covered by the callus ; labial callus thick in 

 the upper part, truncated at the umbilicus. Mouth ovate, large. 



Measurements : Height, 35 mm, diameter, 34 mm (but it grows larger). 



Remarks: I cannot find any difference between the Patagonian fossil 

 and Zittel's figure of the New Zealandian form, except that in the latter 

 the callus is not truncated at the umbilicus. 



In weathering, in this species as well as in N. secunda, a comparatively 

 larger amount of shell substance is removed at the suture, so that the 

 latter appears to be situated in a groove or channel. 



