Width. 





3.00 mill. 



Cotype. 



4.00 " 



Phil. Acad. 



3.50 " 



Coll. Walker. 



3.80 " 



Bost. Soc. N. H. 



3.10 " 



(« << a 



2.50 " 



" " " 



4.00 " 



" " " 



cotype, 



one specimen Smith 



378 THE CHICAGO ACADEMY OF SCIENCES. 



a trifle tumid ; spire acutely conic, a trifle longer than the aperture, 

 nuclear whorls smooth, consisting of 1^4 rounded, horn colored whorls, 

 the second being about four times the size of the first (similar to those 

 of catascopium) ; sutures impressed ; aperture oblong-ovate, narrowed 

 at both extremities; outer lip rather thin, regularly convex, bordered 

 by a red-edged varix within; inner lip narrow, reflected over and 

 rather tightly appressed to the columella, leaving a very small um- 

 bilical chink; there is a well-marked columellar plait. The aperture 

 is produced anteriorly and the shell is frequently quite imperforate. 

 Length. Width. Aperture length. 



13.00 6.50 5.50 



14.00 7.00 7.50 



12.00 6.50 6.50 



14.75 7.00 7.00 



11.75 6.00 6.00 



11.50 6.00 6.00 



15.00 7.50 7.25 



Type: Amherst College, Mass. 

 sonian Institution, No. 8490. 



Type Locality: Shoreham (Storeham, misprint), Lake Cham- 

 plain, Vermont. 



Animal, Jaw, Radula and Genitalia: Unknown. 



Range: (Figure 44). Vermont to Michigan. A species of the 

 Canadian region and of the Transition (Alleghanian) life zone. Future 

 researches will doubtless greatly extend this range. 



RECORDS. 2 



Michigan: Kent Co. (Walker). 



Vermont: Shoreham, Lake Champlain, Addison Co. (Adams; Emmons; 

 DeKay; Roper, B. S. N. H.) ; Lake Champlain (Lea; Walker; Dr. F. B. Wil- 

 son); Larrabee Island, Addison Co. (Dr. H. F. Perkins, B. S. N. H.) ; Higate, 

 Lake Champlain, Franklin Co. (Walker). 



Geological Distribution : Unknown. 



Ecology: Clinging to rocks and stones on the shore of Lake 

 Champlain (Adams). 



Remarks: Pallida has been a puzzle to most conchologists, who 

 have identified it with desidiosa, obrussa, catascopium and elodes. The 

 receipt of a series of shells from the original locality 1 together with a 

 study of a cotype (now in the Smithsonian Collection) received from 

 the author, enables the writer to clear up some of the uncertainty 



2 Only those records are here included which are known to have been 

 founded on the true pallida. Several of the New York records and a few from 

 Canada may eventually prove to have been based on true pallida. Until this 

 fact is ascertained beyond a doubt, it seems best to restrict the range to the 

 known authentic records. 



'Submitted by Mr. C. W. Johnson, Curator of the Boston Society of Natural 

 History. 



