372 AMERICAN JOURNAL 



I am indebted for specimens of this interesting shell to Dr. 

 Hubbard, of Tottenville, Staten Island. They were collected 

 by his son, Mr. V. B. Hubbard, Assistant Surgeon U. S. Army, 

 at whose wish I dedicate the species to his late friend and 

 fellow-Surgeon, R. M. S.Jackson, Corr. Memb. Acad. Nat. Sci., 

 Philadelphia. Dr. Jackson, at the time of his death, a year 

 since, at Chattanooga, was diligently engaged in studying the 

 fauna of that part of Tennessee. 



Helix significans, nov. sp. — Plate 21, fig. 9. 



T. umbilicata, depressa, discoidea, tenuis, irregulariter et 

 leviter striatula, striis subtus subobsoletis, nitens, pallide cor- 

 nea; spira parum elevata; sutura vix impressa; anfr. 6, sub- 

 planulati, ultimus rotundato-inflatus, basi subplanus, circa urn- 

 bilicum excavatus; umbilicus pervius, fere | diametri sequans; 

 apertura obliqua, depressa, lunaris; perist. simplex, acutum. 



Shell umbilicate, depressed, discoidal, thin, with fine irregu- 

 lar stria), which are almost obsolete at the base, shining, pale 

 horn-colored ; spire little elevated ; suture slightly impressed ; 

 whorls 6, subplanulate, the last roundly inflated, rather flat at 

 the base, excavated around the umbilicus, which is pervious, 

 and equal almost to \ of the diameter of the shell ; aperture 

 oblique, depressed, lunate; peristome simple, acute. 



Dimensions. — Diam. maj. 4|, min. 4, alt. 2 mill. 



Habitat. — Fort Gibson, Indian Territory, (V. B. Hubbard !) 



Three specimens were found,- — one apparently adult, the 

 others having respectively 4 and 5 whorls only. 



Remarks. — This species belongs to the group of peculiarly 

 North American type, embraced by Albers in Gastrodonta, 

 subgenus of Hyalina. It is especially allied to H. multiden- 

 tata, Binney, from which it differs in being of larger size, with 

 wider umbilicus, and in the absence in the last whorl of the 

 series of numerous small teeth which characterize Binney's 

 species. 



In a young specimen of H. significans, having four whorls 

 only, there, however, three small teeth, one by itself, and at 

 some distance from it, two others, situated as the teeth are in 

 H. multidentata . Whether these teeth are or not constant in 

 the antepenultimate whorl of H. significans, I am unable to 

 determine. 



