OF CONCHOLOGY. 163 



Hyalina Hornii, Gabb. 



Plate 11, figures 36, 37, 38. 

 " Shell small, openly umbilicate, depressed ; covered with an 

 opaque brown epidermis, which, under the glass, shows minute 

 oblique striations, and a few small, scattered hairs ; whorls 4^, 

 the first 3J, forming a very low, nearly flat spire, the last de- 

 scending much more rapidly ; suture strongly marked, especially 

 between the last and penultimate whorl ; umbilicus occupying 

 about a third of the inferior surface, indistinctly perspective ; 

 aperture oblique, subcircular ; lip simple, inner margins approxi- 

 mating. 



Height -09, diam. -16 inch. 

 Fort Grant, junction of Arivapa and San Pedro Rivers, Arizo- 

 na." — Am. Jour, of Conchologt/, ii. p. 330, 1866. 



Gastrodonta significans, Bland. 



Plate 11, figures 39, 40, 41. 



" Shell umbilicate, depressed, discoidal, thin, with fine irregular 

 stride, which are almost obsolete at the base, shining, pale horn- 

 colored, spire little elevated ; sutare sliglitly impressed ; whorls 

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

 excavated around the umbilicus, which is pervious, and equal 

 almost to one-fifth the diameter of the shell ; aperture oblique, 

 depressed, lunate ; peristome simple, acute. 



Diam. 4-5, alt. 2 mill. 



Fort Gibson, Indian Territory. 



It is especially allied to G. viultidentata, Binney, from which 

 it diff"ers 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 Gr. signijieans, having four whorls 

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

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

 multidentata. Whether these teeth are or not constant in the 

 ante-penultimate whorl of (J. significans, I am unable to deter- 

 mine." — Am. Jour. Conch., ii. p. 372, 1866. 



Spurious Species. 



Helix harpa. Say, belongs to the family Pupadae. 



Helix irrorata, Say,= H. lactea, Mull., a Spanish species. 



Helix Trumbulli, Linsley, = Skenea serpuloides. 



