244 THE rOTOMAC OR YOUNGER MESOZOIC FLORA.. 



Localities: Fi-edericksburg;; fishing hut above Dutch Gap Canal: 

 banks of Dutch Gap Canal. 



This plant is quite abundant at the fishing hut in the forms with 

 narrow leaves, such as are figured in PI. CLXVII, Fig. 5. It is also com- 

 mon in such forms as PI. CXVIII, Fig. 4, etc. It is comparatively rare 

 at the other localities. 



The type of Sequoia illustrated in S. Belchenhachi is much the most 

 common one in the Potomac flora. It is illustrated in such plants as 

 S. ami)i(jua and S. subuJata. Those witli scale-shaped leaves are very rare- 



S. Beichenhachi is the most common conifer at the fishing hut. Nearly 

 all the specimens have the leaves closely placed on the twigs. The twigs 

 branch copiously, and by their size indicate that the growth Avas vigorous 

 All the leaves are widest at base, strongly falcate and acute, decurrent at 

 base, with a distinct midrib, the larger leaves being acuminate. PI. CXX, 

 Fig. 7, shows an unusual mode of insertion of the leaves, they being at 

 right angles with the stem. This position seems to be assumed by the 

 older leaves. As a rule the younger leaves are obliquely placed and 

 strongly curved upwards. The scars left by the leaves after falling off 

 from the older twigs are obovate, rounded at the top, with a round vascular 

 scar at the top and a furrow running down from it (see PI. CXIX, Figs. 4, 

 5). Fig. 4 gives the natural size, and Fig. 5 gives the scars from another 

 stem enlarged. The forms, PI. CXVIII, Fig. 1, and PI. CXIX, Fig. 1, 

 show some differences from the Dutch Gap specimens in having the leaves 

 more remote and obtuse. They look something like Heer's species S. 

 Smithiana. The first-named specimen shows that some of the forms 

 attained very considerable dimensions. In PI. CXVIII, Fig. 4, and PL 

 CXIX, Fig. 3, at the points marked (a), we have the tips of twigs showing 

 a growing bud with undeveloped leaves. 



Sequoia Reichenbachi (Gein.) Heer, var. longifolia, n. v. 



Plate CXVII, Fig. 8. 



Stems comparatively very stout, branching freely, leaves rather re- 

 motely placed, strongly falcate, narrowly linear, widest at base, decurrent, and 

 united to form a narrow wing, very long and acuminate; midnerve slender. 



