514 CALIFORNIA ACADEMY OF SCIENCES 



5000 to 5500 feet elevation, though tlie degree of cold 

 there has not destroyed them. 



3d. The great differences of climate in different zones of 

 the Sierra, cause more distinct limitation of species by differ- 

 ent elevations than in the coast range near the sea shore, but 

 as shown by the distribution of C. traskii and varieties, it is 

 less apparent at a distance from the Bay region, both north- 

 ward and southward, where the two ranges of mountains 

 are crowded together. Toward the coast, every group be- 

 comes more varied into sub-species, and larger colonies of 

 most of them are found. 



4th. The more equable and moister climate near the 

 coast evidently makes it possible for many forms to live 

 together that are more or less limited on the Sierra Nevada 

 to special zones, and this is most apparent nearest to the 

 seashore. 



There is an approach in tlie Santa Cruz range to a higher 

 zone of Vitrinoids and probably of Limacoids. The latter 

 are found, like the Succineas, in the Sierra, both at their 

 base, in damp grounds, and at nearly 6000 feet altitude, 

 though rare between. 



XV. To give a practical point to this long article, it may 

 be remarked, that, althougli the ancient practice of feeding 

 human pulmonates on Helicoid pulmonates as a cure for 

 lung diseases has been justly abandoned (marine mollusca 

 being far preferable i, yet they are still much sought for by 

 European epicures, as great delicacies, and may be worth 

 cultivation for this purpose. 



It may be added that the search for them in the groves 

 around the bays has been found by the writer one of the 

 most beneficial modes of exercise in his own experience, 

 when threatened with pulmonary consumption. Thus they 

 may benefit health without internal use, and make outdoor 

 exercise more interesting to those who need it, than if taken 

 without any other purpose tlian to gain strength. 



