b PROCEEDINGS OF THE NATIONAL MUSEUM vol. 82, art. 8 



CHILINA LIMNAEFORMIS Dall 



Plate 1, Figures 3, 7 



1870. Chilina (Pseudochilina) limnaeformis Dall, Ann. Lye. Nat. Hist. (New 

 York), vol. 9, p. 357. 



1881. Chilina (Pseudochilina) limnaeformis E. A. Smith, Proc. Zool. See. Lon- 

 don, p. 846. 



1911. Chilina linmaeformis Dall, in Pilsbry, Non-marine Mollusca of Patagonia, 

 Reports of Princeton University Expedition to Patagonia, 1896-1899, vol. 3, 

 p. 531. 



This species is the type of the subgenus Pseudochilina Dall, de- 

 scribed at the same time. The subgenus was defined thus : " shell 

 thin, covered with a rough fibrous epidermis; spire elevated, acute." 

 Under the description of the species, he says : " The curious epi- 

 dermis and broad plicate columella alone distinguished this singular 

 shell from a Limnaear As this type (U.S.N.M. No. 56423) has 

 never been figured, a view of it is given in this paper. 



By " fibrous epidermis " Dall probably meant that the axial sculp- 

 ture consists of numerous threadlike incremental lines. In dis- 

 cussing this type specimen Pilsbry said : " The irregular or fibrous 

 surface which served to characterize the subgenus, seems to me to 

 be wholly due to erosion, the cuticle or periostracum being lost from 

 the unique type in the National Museum. In other characters the 

 shell is a typical ChilinaP 



The shell was more or less covered with a deposit of lime and dirt 

 as often occurs with shells, especially those from lacustrine habitats. 

 When this deposit is removed, the periostracum is revealed as present 

 on all but a portion of the front aspect and is normal. The " fibrous " 

 appearance is due to the axial incremental threads underlying the 

 periostracum. Pilsbry is right in thinking the species is not sub- 

 generically different from the genus. The locality quoted, Chile, is 

 indefinite. The shell probably classifies with others having a rather 

 thin shell, and a broad columella with a prominent, nearly horizontal, 

 fold such as C. oldroydae Marshall, and C. iheringi Marshall of the 

 present paper. It may eventually prove to be a young specimen of 

 some already described species. 



U. S. GOVERNMENT PRINTING OFFICE: t9S» 



