216 AMERICAN JOURNAL 



It of course extends to less elevations as we go northward, 

 being limited both by cold and by the absence of lime, as will 

 appear hereafter.* 



San Gorgonia Pass, latitude 34°, altitude 3,000 feet. This 

 is apparently a good locality, Mr. Voy having found there H. 

 arbor ea, Say, (exactly like eastern specimens !), C. chersina, Say, 

 (which I also found near Lake Taho, latitude 39°, altitude 

 6,100 feet) differing apparently in larger size than east, P. 

 miwuscula, Binn., (teste Newcomb,) which seems to extend with 

 the two preceding, across the continent. These he found in the 

 mountains several thousand feet above the pass itself. 



In Cajon Pass, immediately north of this, elevation 4,676 

 feet, I failed to find any species, though my journeys through it 

 were too hasty for a careful search for small ones. I also tra- 

 versed San Francisquito Pass, farther north, 3,718 feet altitude, 

 and searched carefully near the summit with the same bad suc- 

 cess, although water, lime and vegetation, the three great requi- 

 sites for land shells, were abundant. Not even a dead sheil 

 occurred, yet from the usually limited local range of most of 

 the species, even where numerous, they may occur very near 

 where I sought for them in vain. Trees are more abundajit in 

 or above t'he San Gorgonio Pass. 



Temescal Mountains. — These form a small range about 

 thirty-five miles south of Cajon Pass, seventy north of San 

 Diego, twenty-five west of San Gorgonio and thirty-five from 

 the coast. This is the central point for M. JYewberryana, W. G. 

 B., a rare species in collections. Prof. W. H. Brewer obtained 

 numerous dead bleached specimens and a few living ones, show- 

 ing that they are probably abundant in a limited range. I found 

 one young specimen twenty miles north of San Diego, paler 

 than the adult and not unlike M. Vancouverensis, for which they 

 have doubtless been mistaken by former collectors in that region. 

 Limestone and tin ore are found in this range. Most of the 

 main range south of this point being granitic, there is little 

 probability of any species being numerous in that direction. 



Several Lower Californian and Mexican species have been 

 credited to California, but not recently obtained, and may have 

 been collected east of the Colorado. 



On the eastern slope of the dividing ridge at the entrance of 



*I have elsewhere mentioned the occurrence of hybrids between dif- 

 ferent species, usually when nearly allied. I have one specimen received 

 from Dr. Newcomb (locality unknown), which combines the characters 

 of tudiculata and Mormonum, two of the most different species in our 

 banded series. 



