THE NAUTILUS. 



as long as the three preceding, inflated and convex, body-whorl large 

 and well rounded ; lines of growth strong and regular, cut by numer- 

 ous fine spiral lines giving a shagreened appearance to the surface, 

 in some specimens the last half of the body whorl is obsoletely mal- 

 leated ; aperture broadly oval, somewhat more than one-half of the 

 entire length of the shell, dark brownish-yellow within, with a liver 

 colored band just within the lip ; lip sharp, regularly rounded and 

 slightly expanded toward the basal margin ; columella thick, white 

 with a strong fold, broadly reflected over and appressed to the axial 

 region, leaving only a very small perforation, and connected with the 

 upper insertion of the lip by a broad white and rather thick (for the 

 genus) callus ; axis thick, solid, twisted. 



Alt. (Fig. 8) 22; diam. 13^; length of ap. 13; width 10 mm. 



Alt. (Fig. 11) 24; diam. H ; length of ap. 14; width 10 mm. 



Type (No. 21345, coll. Walker) from Washington Harbor, Isle 

 Royale, Lake Superior, Mich. Cotypes in the collection of the 

 Philadelphia Academy and Chicago Academy of Sciences. 



Immature specimens of this species were first taken by the Uni- 

 versity of Michigan expedition of 1904, and in the report of that trip 

 (Rep. Geol. Surv. Mich., 1905, Separate, p. 97) was stated to be 

 " related to L. sumassi Bd., but probably undescribed." 



The expedition of 1905 was fortunate in securing fully-matured 

 specimens. And a comparison of these with a photograph of cotypes 

 of sumassi from the British Museum, kindly furnished by Mr. F. C. 

 Baker, of Chicago, showed that the two forms were entirely dis- 

 similar. 



The affinities of pilsbryana are entirely with L. emarginata Say, 

 a species of general distribution through the Great Lakes from 

 Saginaw Bay northward. 



It differs from that species in its darker color, more inflated whorls, 

 especially those of the spire, and the entire absence of the emargina- 

 tion characteristic of that species. 



L. emarginata was also found on Isle Royale, and there main- 

 tained the acute conical spire with a less impressed suture charac- 

 teristic of the usual form of that species. The axis of the Isle Royale 

 emarginata (fig. 1) is more slender, more curved and less twisted 

 than that tf pilsbryana (fig. 2). Both of these figures are made from 

 immature specimens. 



