CHAPTER XX. 



Patula Strigosa — Its Many Forms — The Zonites — 

 Many Species — Macrocyclis — The Glass-Snail — 

 The Slugs — Limax — Ariolimax Columbianus — A 

 Valuable Reference-Book. 



r PHE most abundant snail found between the Rocky 

 1 and Sierra Nevada mountains bears the name 

 Helix (Patula) strigosa, Gould, Pat'-u-la stri-go'-sa. 

 It assumes very many forms, one of which is shown 

 in Fig. 131. Another variety has a smooth surface, 

 and in general form closely resem- 

 bles Fig. 127, on a previous page. 

 The shell has a broad umbilicus, 

 a nearly circular aperture, and a 

 sharp lip. The whorls are five in 

 number, and in most specimens the 

 spire is low. The whorls of some varieties are 

 crossed by distinct ribs, in others, as shown in Fig. 

 131, they are banded by raised, spiral ridges, while 

 the shells of many specimens are almost smooth. 

 The whorls of many of the shells are marked with 

 two brown stripes, but some are quite destitute of 

 this ornament. The average diameter of the shell is 

 rather less than an inch, though some specimens are 

 much smaller. 



The fine set of specimens of this greatly varying 

 species, belonging to the cabinet of Mills College, 

 were mostly collected from different parts of Utah by 

 Mr. Henry Hemphill, whose investigations upon this 

 species have been of the greatest value to science, and 



