OF NORTH AMERICA. 241 



L. cubensis. Havana specimens of the latter are absolutely indistin- 

 guishable from Vermont L. umbilicata in our collection, received from 

 Prof. Adams himself." Dr. Pilsbry's opinion was based on an authentic 

 lot of umbilicata received from Prof. Adams, as stated above. It is 

 interesting to note that both Crosse and Fischer, as well as Von Mar- 

 tens, have considered umbilicata a synonym of cubensis. Later Mr. 

 Bryant Walker examined a cotype deposited by Adams in the Museum 

 of Middlebury College. This specimen has been compared with ma- 

 terial from Rhode Island and from Aroostook County, Maine, and the 

 distinction of the species is beyond question. Pilsbry (op. cit., p. 321) 

 suggested its relation to techella when he remarked : "L. techella Hald. 

 is nearly identical with umbilicata!' To Mr. Walker belongs the credit 

 of finally settling the question of the standing of this neat little species, 

 although he did not sufficiently differentiate it from cubensis. 



Adams' reference of the species to Jamaica shows that he confused 

 his species with cubensis, described a year earlier, and indicates the 

 relationship of the two species. At one time it was the positive opinion 

 of the writer that Adams had mixed his shells with the Jamaica ma- 

 terial collected by him, but later researches have proven this opinion 

 to be erroneous. 



The Maine specimens, referred previously to humilis, are quite 

 typical and, indeed, may be taken as the type of the fully mature form. 

 They accurately correspond with the description of Adams, showing 

 the inflated body whorl, the faintly impressed spiral lines and the short 

 spire. In outline these shells strongly resemble a miniature caperata 

 and it is no wonder that conchologists have so generally mistaken 

 this species for the widely distributed caperata, when half grown. 



Umbilicata was at first thought to group with cubensis, as pointed 

 out by Pilsbry and Walker, but its radula has tricuspid lateral teeth, 

 while in the cubensis group the laterals are bicuspid. This structure 

 of the radula allies umbilicata with the humilis group, in which the 

 laterals are tricuspid. Upon close inspection the shell is seen to be of 

 the same general form as parva, sterkii, etc. Lea's griffithiana is abso- 

 lutely synonymous with umbilicata, his shell, as well as others collected 

 in New York state, being indistinguishable from the shells from Rhode 

 Island and Maine. Many of the references to humilis from the Eastern 

 and Middle states probably refer to this species. 



Galba cyclostoma (Walker). Plate XXX, figure 8. 

 Limn&a cubensis WALKER, Rev. Moll. Mich., p. 17, 1894. 



Lymncca cyclostoma WALKER, Nautilus XXII, No. 1, p. 7, pi. II, fig. 4, May, 

 1908. 



