396 THE CHICAGO ACADEMY OF SCIENCES. 



TYPES : Chicago Academy of Sciences, four specimens, No. 23800 ; 

 cotpyes, collection Miss Mary Walker, Buffalo, N. Y., Mr. Bryant 

 Walker, Detroit, Mich., Academy of Natural Sciences of Philadelphia, 

 and the Smithsonian Institution, Washington, D. C. 



TYPE LOCALITY : Crystal Brook, Long Island, N. Y. 



ANIMAL, JAW, RADULA and GEN ITALIA : Unknown. 



RANGE: (Figure 43). Long Island. A species of the Alleghanian 

 division of the Transition life zone, and of the Nova Scotian region. 



RECORDS. 



Canarsie, King Co. (Ferriss; Weeks); Crystal Brook and Mt. Sinai, Suf- 

 folk Co., Long Island, N. Y. (Miss Walker and Bryant Walker). 



GEOLOGICAL RANGE: Unknown. 



HABITAT : In salt or brackish water "at low tide in shore of bay 

 fed by springs" (Crystal Brook). In ice-cold spring (Mt. Sinai). 



REMARKS: This peculiar Lymnsea was at first thought to be a 

 variety of catascopium but it differs from that species in its thinner 

 shell, more globose whorls, especially the spire whorls, and particularly 

 by its triangular, smooth, reflected inner lip and distinct umbilical 

 chink. The form of the shell and of the inner lip resemble the techella 

 group of Lymnaeas of the subgenus Galba. 



It is probably a variation of the catascopium stock, produced by 

 changing conditions of the environment which have dwarfed the shell. 

 It is a significant fact that the icy cold spring at Mt. Sinai has pro- 

 duced the same shell characteristics as the brackish water of Crystal 

 Brook. There is considerable variation in the height of the spire 

 among the numerous specimens examined, some individuals having an 

 elongated spire a trifle longer than the aperture while in others the 

 spire is less than half the length of the aperture. The shell also varies 

 in corpulency. The short globose shells are all immature and are the 

 specimens first described as typical. Additional specimens from 

 Crystal Brook and also from Canarsie show the mature form to have 

 a spire as long as the aperture with rounded whorls. A single speci- 

 men from Canarsie is distinctly scalariform (plate XLI, figure 6). 

 The inner lip is peculiar and, together with the form of the shell, will 

 easily separate this species from catascopium, its nearest ally. The 

 short spired form was at first thought to be a variation of catascopium 

 pinguis, hence the specific name pseudopinguis. 



The shell was first brought to the notice of the writer by Miss 

 Mary Walker of Buffalo, New York (who suggested its resemblance 

 to bulimoides) and later by Mr. Bryant Walker of Detroit, Michigan. 



