ACADEMY OF NATURAL SCIENCES. 227 



metamorphosed sandstone. Should these two species be definitely united, after 

 a thorough investigation, they would afford a most striking example of the influ- 

 ence of a different soil. It is certainly singular to find such a well-characterized 

 form restricted to one locality only. This fact, however, would not stand iso- 

 lated with us here ; Abies bracteata, wa find similarly confined to one locality 

 only in California. Isolation is more or less a characteristic feature with all 

 our trees, and there is probably no country where the influences of soil, climate, 

 and exposition are so well and abruptly marked and unmistakably defined. 



6. Pinus muricata, Don. 

 Monterey ! Mendocino City ! 



In a moist depression at Monterey, I found a small group of this species, 

 averaging about fifteen feet in height, and five to six inches in diameter. Bark 

 reddish and nearly smooth ; branches almost at a right angle with the main 

 axis and generally from five to seven in a whorl ; leaves of a darker vivid green, 

 and more succulent and longer, than those of Pinus insignis, of which there 

 were trees of the same size by the side of it ; cones from three to seven, in a 

 whorl very much aggregated and clustered. I counted seventeen whorls on a 

 tree fifteen feet high. The lower portion of the trunk was clad with dead leaves. 



At the same distance (about two miles) from the ocean, and scarcely a mile 

 from the above-mentioned depression, I found another group (mixed with 

 Cupressus macrocarpa) in a deeper but drier locality. Here the tree was alto- 

 gether of a different aspect, inferior in all its parts. This very transition sug- 

 gested strongly, that this pine and the one previously seen on the plains near 

 Mendocino City, on a similar soil, might be of the same species. 



Near Mendocino City, on the so-called plains, I found in great abundance a 

 small pine tree, which I refer for the present to this species. 



Height, five to twenty feet, but the greater number averaged only from five 

 to fifteen feet. Only one tree which I noticed which was fifty-five inches in 

 circumference, and twenty to twenty-five feet in height. It had a flattish top 

 with the branches very much imbricated and so completely covered with cones, 

 that it was really difficult to discover its foliage. But this tree was very excep- 

 tional, compared with the mass of little trees covering the plains. These had 

 in general upright branches with numerous and slender branchlets ; leaves 

 shorter, denser, and of a darker green than Pinus contorta ? which grows with 

 it and is a larger tree altogether ; bark reddish, very thin, exhaling a strong 

 resinous odor, and but slightly rimose ; cones two to four inches long (curved 

 when long) and scarcely an inch thick, mostly in pairs, but sometimes in threes, 

 reflexed. I counted fifteen sets of cones on a tree fifteen feet high. 



7. Pinus contorta, Dougl. ? 



Head of Tomales Bay ! Mendocino City ! 



Its manner of growth resembles that of Pinus insignis very much. It attains 

 the same height, has the same irregular spreading branches, the same thick 

 rimose bark and very resinous wood. The leaves are invariably in pairs and 

 slightly silvery on the lower surface. The cones are scarcely two inches long 

 with mostly reflex pedicles (umbo) on the slightly gibbous side and persistent 

 for a great number of years. 



