FOSSIL FLORA. 761 



DESCRIPTION OF SPECIES. 



Sequoia magnifica n. sp. 

 Pis. CIV, CV, CX, OXI, CXVII, figs. 1-6. 



Diagnosis. — Trunks often of great size, 6 to 10 feet in diameter, 30 feet 

 high as now preserved, bark when present 5 or 6 inches in thickness; 

 annual rings very distinct, 2 to 3 mm. broad; fall wood reduced to narrow 

 bands of 3 to 15 rows of thick-walled cells; cells of spring and summer 

 wood large, hexagonal or often elongated; resin tubes numerous, composed 

 of short cells ; medullar}" rays numerous, of a single series or occasionally 

 with a partial double series of superimposed cells; wood cells with one or 

 two rows of small circular pits. 



Transverse section. — In this section (Pis. CX, CXI) the structure appears 

 beautifully preserved. The rings are rather narrow, being only 2 or 3 mm. 

 broad, or often only 1 mm. They are very sharply demarked, even to the 

 naked eye. Under the microscope the rings are found to consist of a band 

 of thick-walled cells that is never more than 15 rows of cells deep and 

 often is reduced to 2 or 3 rows. The cells composing the spring and summer 

 wood are of uniform size and inclined to be hexagonal in shape. Those of 

 the fall wood are, of course, compressed. 



The resin cells are numerous and may be readily distinguished by 

 the dark contents. They occur mainly in the spring and summer wood. 



The medullary rays seen in this section are long, straight, and sepa- 

 rated by usually about 3 rows of wood cells. 



Radial section. — This section (PL CXVI, figs. 2-3) is the least satisfactory 

 of all. The wood cells show well under the microscope, but their markings 

 are very obscure. B}- prolonged search it is made out that the pits are in 

 1 row, or sometimes 2 parallel rows. They are small, as far as can be made 

 out, and are too obscure for satisfactory measurement. 



The rays are composed of long, unmarked cells. 



Tangential section. — This section (See PI. CXVI, fig. 1) is very satisfactory. 

 The wood cells are long and unmarked. The resin ducts are numerous, 

 but scattered, the cells being twice or three times as long as wide. In 

 many cases they are filled with or contain masses of dark material, repre- 

 senting the resin now turned to a carbonaceous mass. 



