OP coNcnoLOQY. ' 253 



20. Hyalina ferrea, Morse. 



Plate 4, figure 33. 

 Whorls 3, not shining, steel grey ; last whorl rapidly en- 

 larging ; aperture very large, well rounded; spire slightly 

 elevated, suture distinct, deeply channeled near the apex; 

 umbilicus small and abrupt, exhibiting all the volutions; 

 periostraca minutely marked with fine revolving lines. 

 Diam. 2-5, height 1-25 mill. 



Maine. 



Distinguished from H. electrina by having fewer whorls 

 and being smaller in size, also in having a larger umbilicus 

 and revolving strias. 



Mexican Species. 

 Hyalina bilineata, Pfeiffer. 



Plate 4, figure 30. 



Whorls 5, shining, light horn color, with a narrow brown 

 band above the periphery and another below the suture; spire 

 slightly elevated, suture not much impressed; umbilicus nar- 

 row. 



Diam. 15, height 7 mill. 



Hyalina zonites, Pfeiffer. 



Plate 4, figure 29. 



Whorls 6, closely and roughly striate, shining, light horn 

 color, with a narrow, brown band revolving above the peri- 

 phery, and scarcely concealed above by the spire ; spire some- 

 what elevated, suture distinct ; base with the striae not half so 

 numerous, and much more polished; umbilicus moderate. 



Diam. 25, height 12o mill. 



