CHAPTER XVII. 



Dextral Shells Again — Species of Limnophysa — A 

 Brother's Tribute — The Two Great Limn je as— 

 Ear-Shells — Carychium and Melampus — Torna- 

 tina and the barrel-shell — bubble-shells — sea- 

 Slugs and Their Beauty — Farewell to the Ocean 

 Home. 



LEAVING now the left-handed Physas, let us 

 examine their dextral neighbors, which also live 

 in lakes and streams, and are similar in their habits 

 to those we have studied. Nearly all fresh -water 

 shells are covered with a greenish brown epidermis, 

 and where this becomes broken, as it frequently does, 

 near the apex, the shell becomes eaten or eroded by 

 the weak acids which are usually present in the 

 waters of lakes and streams. 



Of the species which we are to notice, the first is 



named Leptolimncza Kirtlandiana, Lea, Lep-to-lim- 



ne'-a Kirt-land-i-an'-a, and a view of it is given in 



Fig. 109. The shell is dextral and somewhat 



cylindrical; the spire is long andfive-whorled; 



the aperture is rather small and oval, and the 



columella is marked with a fold. The cut is 



somewhat magnified, as the natural size is 



from one-half to three-fourths of an inch. 



Fig. 109. prom near Logan, Utah. 



Limnophysa desidiosa, Say, Lim-no-fi'-sa de-sid-i- 

 o'-sa, has a slender, dextral shell, with a conspicuous 



