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PATAGONIAN EXPEDITIONS I PALAEONTOLOGY. 
ever, describe the surface of L. insolita as smooth, and, indeed, in most 
of the specimens it appears so. But this character is produced by fossili- 
sation, the fine striae being distinctly visible only in very well preserved 
individuals. This character has been ascertained already by v. Ihering. 
We possess young shells that agree in every respect with Philippi’s L. 
arcmcana , they being less oblique than the older ones. 
V. Ihering (1899, p. 40, footnote) doubts the identity of the New 
Zealandian and Patagonian form. Zittel’s figure of L . insolita represents 
a very large specimen, which is very oblique, and which is smooth. That 
the latter character does not agree with the Patagonian fossil has been 
mentioned, but since the latter was described originally and erroneously 
as smooth, it is very probable that also in New Zealandian specimens, in 
well preserved individuals, a striation may be present. The external 
form does not warrant a specific separation, since among our Patagonian 
material the obliquity of the shell varies considerably in individuals of 
the same size, and since also — as has been said above — young individuals 
as a rule are less oblique. Accordingly, the very oblique shape of the 
figure given by Zittel may be due to age. In the configuration of the 
area I do not find any differences : although it is hard to understand 
Zittel’s description in this respect (“area — traversed by a narrow, slightly 
depressed, very indistinct, triangular groove”), his figure corresponds to 
what we see in the Patagonian fossil : below the apex, there is, on the 
area, a broadly-triangular depression on a slightly lower level than the 
lateral parts of the area, and separated from the latter by a sharp, angular 
line. This triangular depression is slightly concave in the middle. 
Record of specimens : Mouth of Santa Cruz River, 175 isolated speci- 
mens, and many more imbedded in matrix ; Las Salinas, 1 sp. 
Distribution: Santa Cruz (Sow.); La Cueva and Jegua quemada (v. 
Ih.). According to v. Ihering in both the Patagonian and Suprapata- 
gonian beds. 
Navidad beds of Llancahue, Chili (Phil.). New Zealand (Zittel), 
Miocene Pareora beds (Hutt.). South Australia, in so called “Eocene” 
(? Miocene) beds (Tate). 
Affinities: By the very strongly developed obliquity, by the very broad 
triangular groove of the area, by the lack of crenulations of the inner 
margins, this shell represents a very peculiar type of the genus, that 
cannot be brought into closer relation to any of the known species. The 
