M'Nab — A Revision of the Species of Abies. 685 



^o- inch. wide. Buds covered with brownish scales, which are very- 

 resinous. 



Transverse section of leaf. — Leaf flattened, about three times 

 broader than thick, sides rounded, upper surface with a faint longi- 

 tudinal furrow, below with a slightly prominent midrib. Hypoderma 

 wanting ; very rarely there are one or two cells at the rounded 

 margin, and one or two below the fibro-vascular bundles. The resin- 

 canals are placed in the parenchyma of the leaf, and although sometimes 

 running very near the lower surface, are always separated from the 

 opidermis by chlorophyll-bearing cells. The pallisade parenchyma is 

 well developed on the upper side, as the stomata rarely extend down 

 the leaf for any distance, although occasionally a single row may 

 run for about two-thirds of the length ; below, the parenchyma 

 has intercellular spaces communicating with the stomata. 



The fibro-vascular bundle is double, the whole surrounded by a 

 well-marked sheath. 



The figure (Plate 47, fig. 11) is drawn from a specimen grown in 

 the Royal Botanic Garden, Edinburgh. 



I have examined five specimens of this species : one specimen 

 :grown in the Boyal Botanic Garden, Edinburgh ; one from Mr. Syme, 

 Elvaston IS'urseries ; two specimens are from Kew Herbarium — one 

 marked "P. balsamea. Canada, Mr. Perceval;" the other, "P.balsamea, 

 L. Gonan ;" the fifth specimen is from the Museum, Royal Botanic 

 'Garden, Edinburgh. The leaves examined are from the base of a 

 cluster of cones, and are very interesting, as having a considerable 

 quantity of hypoderm developed. Like P. lasiocarpa, this species is 

 bifolious, and the leaves resemble those of P. Fraseri. Indeed, I find 

 it very difficult to separate the two forms, viz., Fraseri and balsamea, 

 by characters derived from the structure of the leaf. 



10. Pinus {Ahies) sihirica, Turcz., Cat. Baekal, No. 1067 ; Parlatore, 

 D. C. Prod. vol. xvi. pars 2, p. 425, No. 101. Abies sihirica, 

 Ledeb. Fl. Alt. 4, p. 202. Picea Pichta, Loud. Arbor. Brit. 4, 

 2338. Ahies Pichta, Forbes, Pin. Wob. 109, t. 37. 



Shoots hairy or smooth. Leaves inserted singly and close together 

 ;all round the shoot, those on the under side bent to form two lateral 

 rows, those on the upper side directed with their points upwards and 

 forwards towards apex of the shoot. Leaf linear, twisted above the 

 base, which is slightly narrowed towards the orbicular insertion, width 

 nearly uniform throughout the entire length, apex rounded or slightly 

 truncate, upper surface dark green, with no stomata, beneath with a 

 band of stomata on each side of the midrib, there being from 4 to 5 

 rows in each band. Leaves from ^ to \^ inch long, and about xs" inch 

 wide. Buds brownish, and very resinous. 



Transverse section of leaf. — Leaf flattened, about three times as 

 broad as thick, sides rounded, upper surface with a slight longi- 

 tudinal furrow, below with a very faintly prominent midrib. Hypo- 

 derma entirely absent. The resin-canals are placed in the parenchyma 



