242 CALIFORNIA ACADEMY OF SCIENCES. 



prepared to dispute that, bat believe that further develop- 

 ments are needed to decide it. It is evident that the terti- 

 ary and quaternary fossil bones have been all mixed up by 

 volcanic and glacial action. There is, however, no doubt 

 that this skull and others described from the Sierras, prove 

 man's existence in the early quaternary, or about the end 

 of the pliocene epoch. 



Supposing the specimen of Helix Mormonum found with 

 it to be of the quaternary, its close resemblance to the liv- 

 ing form now existing in the vicinity, indicates to some ex- 

 tent a climate nearly like the present. The extinct tertiary 

 vegetation of the Sierras, was doubtless accompanied by 

 land shells as different from those now living there, as the 

 greater part of the trees differed, find like them may have 

 more resembled those of the present group found around 

 the Gulf of Mexico. Their probable characters may be in- 

 ferred from those of the fossil land shells of the Rocky 

 Mountain tertiary described by Dr. White and others. 



Besides this, the only fossil Helix yet seen from the 

 Sierras, is the one before mentioned as having been named 

 "H. Carpenteri" when first found, but very different from 

 the type, and indeed more like a variety of H. tudiculata. It 

 is, however, distinct enough to indicate great antiquity, and 

 will probably rank as an extinct species when more spec- 

 imens can be obtained. Having the elevated imperforate 

 form of the species now living close to the sea shore, I have 

 already mentioned it as probably having lived on the east- 

 ern shore of the pliocene inland sea once filling Tulare 

 Valley, near where it was discovered in the tertiary (or 

 later) formation by Mr. Gabb. When that sea or lake ex- 

 isted, the Sierras really formed the shores of the continent, 

 and such parts of the Coast Ranges as were above water 

 must have been peninsulas or islands many miles distant. 



In the Coast Ranges there have been no fossil land shells 

 found that can be distinguished as species from those living 

 near them, which, however, is only negative testimony to- 



