M'Nab — A Revision of the Species of Abies. 699 



dermis. The pallisade tissue is -vrell developed on the upper side, and 

 below is the parenchyma with well-marked intercellular spaces com- 

 municating with the stomata. 



Fibro-yascular bundle double, the parts placed close together, 

 with a few thick liber-like cells above and in the middle. The whole 

 is surrounded by a well-marked sheath. 



The resin-canal has a double wall — the inner cells smaller and with 

 thin walls, the outer larger and with thick walls ; this thick- walled 

 layer being in contact with the lower epidermis. 



Only one plant of this species has come under my notice. It has 

 been long cultivated in the Royal Botanic Garden, Edinbiu'gh, and 

 was sent to me by my father, marked " Picea sp., California, old tree." 

 The unique plant in the Edinburgh Garden was raised from seed sent 

 from the Eocky Mountains by Drummond. The cone being unknown, 

 I have not attempted to name it. 



The figure (Plate 49, fig. 28) is drawn from the plant in the Edin- 

 burgh Garden. 



The leaf is somewhat like that of P. pectinata, but the plant is not 

 a handsome one. 



II. PsEunoTsiTGA, Bertrand ; Carriere (in part). Abies, Auct. Tsuga, 

 Carriere. Keteleeria, Carriere. 



1. Pinus [Pseudotsuga) nobilis, Douglas, MSS. ; Parlatore, in D. C. 

 Prod, xvi., pt. ii., p. 419, ^o. 89. 



Shoots covered with fine hairs. Leaves inserted singly all round the 

 stem, very close together, the leaves on the lower side of the shoot 

 directed laterally by being curved outwards, but not twisted at the 

 base ; those on the upper side of the shoot all directed upwards. Leaf 

 rigid, linear, more or less falcate, with an obtuse apex, upper sur- 

 face variable, sometimes with numerous stomata, the whole surface 

 being pale in colour, at other times stomata less numerous, or even 

 wanting, and the colour darker ; beneath with a band of stomata on 

 each side of the midrib, between the midrib and the resin-canal, some- 

 times with stomata between the external margin of the resin-canal and 

 the edge of the leaf, there being 5 to 7 rows of stomata in each of the 

 bands between the midrib and resia-canal. Leaves about 1 to H- inch 

 in length, and about iV inch wide. Buds small, dark-coloured, and 

 covered with resin. 



Transverse section of leaf. — Leaf broadly triangular, three times 

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

 tudinal furrow, below with a prominent midiib. Hypoderma conspi- 

 cuous, a single layer, rarely a double layer, at the rounded margin of 

 the leaf ; a number of hypoderm cells above, under the longitudinal 

 furrow, and a considerable mass two or more cells thick at the prominent 

 midiib below ; the hypoderma is interrupted above between the 

 central furi'ow and the margin by the presence of stomata. The 



