560 CALIFORNIA ACADEMY OF SCIENCES. 



C. Pupoid species: 9. Fujnlla coiynlenta. 



D. Succinoid species: 10. Succinea strctcMana. 



The other species of the Sierras have been named in 

 several previous articles, being about fifteen besides those 

 here named. (See Binney's 2nd Suppl. to Terr. Mollusks.) 



Of this list Nos. 1, 2, 3, are well-known to be widely 

 spread in the Northern States, No. 7 found also in the coast 

 range of California, Nos. 9 and 10 only in the Sierra Ne- 

 vada, and No. 8 so far only near this locality. No. 4 was 

 traced south only about 50 miles by Voy, No. 6 to about 

 lat. 32° 30', while No, 5, very small here at its northern 

 limit, becomes "common in the foothills a mile or two 

 north of Pose creek " (Gabb), as the larger variety car- 

 penteriana, and continues to Guadalupe Island, Lower Cali- 

 fornia. 



Thus it appears that Nos. 4 and 5 overlap in their range 

 for at least 50 miles, and are found together for that 

 distance unconnected by intermediate forms, though both 

 'can be connected with H.fidelis by links now existing north 

 ^nd west. It seems to me, therefore, that No. 5 must either 

 have reached this N. E. corner of its range from the 

 ■direction of the fossils of Eastern Oregon, by way of the 

 east side of the Sierra Nevada (the connecting chain being 

 now extinct there) or has come from the south and west- 

 ward, thus reversing the usual course of migration. 

 For it is well known that the Sierra Nevada are much older 

 than the Coast Mountains, and that the latter are older to- 

 ward the north than the south, thus compelling a southward 

 migration among all land animals during their gradual ex- 

 tension over the country. However this question may be 

 looked at. No. 5 is unlike an}^ other of the Californian banded 

 Helices in crossing the southern end of the valley between 

 the two ranges of mountains, reappearing on the east slope of 

 the Coast range 58 miles farther south, upon tertiary fossil 

 limestone, at an elevation of about 4,000 feet, where no other 

 species is known to occur, near the summit of the Uvas 



