140 NATURAL HISTORY BULLETIN. 



usually readily marks the fossil. The fossil form is widely 

 distributed in the loess, being one of the characteristic 

 species of that deposit, and has usually heretofore been 

 regarded as extinct. In the paper cited, Pilsbry says that 

 "this form is interesting as being the only well-defined 

 species of loess fossil which seems to have become extinct," 

 and that has been the universally accepted opinion. 



However, in 1898* Pilsbry described a living species of 

 Pyramidula from New Mexico and Colorado under the 

 name P. cockerellii. While at Washington two years ago 

 the author had an opportunity, through the kindness of 

 Mr.- C. T. Simpson of the Smithsonian Institute, to exam- 

 ine shells of that species, and was at once struck by their 

 resemblance to Zonites sliimekii. Indeed, Mr. Simpson 

 himself had named a set of the fossil shells P. cockerellii! 

 Through the kindness of Rev. E. H. Ashmun, the author 

 subsequently received three sets of P. cockerellii number- 

 ing thirty specimens. They are from LaBelle (one of the 

 type-localities) , Estes Park and Red River, in New Mexico. 



A careful comparison of these shells with our fossil leaves 

 no doubt of their identity. The recent shells are some- 

 what more depressed than many of the fossils, but among 

 the latter are specimens which are even more depressed 

 than the most extreme recent forms. Moreover the dimen- 

 sions of the types, recorded by Pilsbry, indicate some 

 variation in this character in the recent shells. In every 

 detail of form, size, apex, sculpture on upper and lower 

 surfaces, thickness of shell, tendency toward formation of 

 peripheral angle except on the last third of the fully- 

 formed body-whorl, size of umbilicus, etc., the fossils are 

 like the recent shells, and Pilsbry 's description of P. cock- 

 erelli exactly fits them in every detail which is still dis- 

 cernible iu fossil shells. 



A comparison of the original descriptions of Z. sliimekii 

 and P. cockerellii is facilitated by bringing them together 



* Nautilus, vol. xii, p. 85, December, 1898. 



