PATAGONIAN EXPEDITIONS : PALAEONTOLOGY 
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Distribution : This species has not been found previously in the fossil 
state, but is known living from the Falkland Islands and the Straits of 
Magellan along the western coast of South America. 
Fam. NA TICIDAH Forb. 
Gen. NATICA Lmck. 
1 1 7. Natica chiloensis Philippi. 
PI. XXXIII, Fig. i“A 
1887 N. c. Philippi, Tert. & Quart. Verst. Chiles, p. 89, pi. 10, f. 12. 
1899 TV. c. Ortmann, in: Amer. Journ. Sci., v. 8, p. 431. 
Shell ovate, thick, smooth, except for lines of growth. Spire conical, 
about % of the height of the shell. Umbilicus small. Callus very thick, 
covering most of the umbilicus. Mouth ovate, not dilated. 
Measurements of a very large specimen : FI eight, 34 mm, diameter, 
25 mm, height of mouth, 2 1 mm ; of a smaller one : height, 24 mm, 
diameter, 19, height of mouth, 15 mm. 
Remarks: This species is recognized by the oval outline (which is, 
however, a little variable), by the thick and solid shell, and the thick cal- 
lus. The callus leaves only a narrow slit open at the umbilicus. 
N. gance of Philippi (Cretaceous of Quiriquina) is allied, but has a 
higher spire (one-third of the height of the shell), while in N. chiloensis 
it is between one-fourth and one-fifth, rarely more than one-fourth. The 
external form is a little variable in our species, some individuals being 
more rounded. The callus of the inner lip is very thick, suddenly nar- 
rowed near the umbilical region, leaving a narrow, oval or crescentic 
opening at the umbilicus. The suture is not impressed : in larger indi- 
viduals, however, where the outer layer of the shell is exfoliated, the 
suture appears as a deep groove giving a scalariform appearance to the 
spire, a feature which reminds one of N. chilina and anca d’Orb. from 
Puerto de Hambre. 
One individual from horizon III (upper) has the callus in the umbilical 
region broader, with the slit hardly visible, and approaches thus (as also 
in the more globular form) N. pachystoma Hupe from the Navidad beds 
(see Philippi, 1887, pi. 10, f. ia), to which also N barroisi Phil, seems to 
