THE PACIFIC COAST. 21 



ones flattened, the last convex, rounded below, and slightly 

 deflected at the aperture ; umbilicus broad, showing all 

 the volutions clearly ; aperture oblique, transversely-lunar ; 

 in young specimens the decussated sculpturing of the shell 

 on the parietal wall of the aperture is covered with a light 

 callus as the animal grows, and elegantly marked with 

 numerous fine, crowded, spiral lines ; in mature specimens 

 this beautiful marking is entirely obliterated by the depo- 

 sition of callus, but on breaking the shell, the lines will be 

 found to exist within ; peristome simple, acute, thickened 

 within, ends slightly approximated, joined with a white 

 callus. 



Greater diameter, 37 ; lesser, 20 ; height, 13 millimetres. 



Geographical Distribution. Found in considerable quan- 

 tity by Dr. J. S. Newberry, of the Colorado Exploring 

 Expedition, (Lieut. Ives,) within a few miles of San 

 Diego. 



Remarks. This species bears no close resemblance to 

 any known American Helix. It belongs to the same 

 group as H. Vancouverensis Lea, but differs in size, color, 

 number of whorls, umbilicus, want of peculiar depression 

 of the lip, by its beautifully decussated surface, and pecu- 

 liar parietal wall of the aperture. In form alone, dead 

 specimens may be compared with H. algira Lin., of 

 Europe, but the spire is flatter and umbilicus larger. 



I am unacquainted with any other species of Helix, 

 distinguished by a like peculiarity of the parietal wall of 

 the aperture. 



Named in honor of Dr. J. S. Newberry, the Geologist of 

 the Colorado Ex. Ex. 



Very abundant at the locality given above. But few 

 fresh specimens were brought, however, owing to the fact 

 of there having been a drought for several years before the 

 visit of the Expedition. 



