M'Xab — A Revision of the Species of Abies. 675 



■a prominent midrib. Hypoderma Tvell developed, a continuous band 

 of thickened cells running underneath the epidermis of the upper 

 surface, from the external margin of the one resin -canal to the ex- 

 ternal margin of the other. At the rounded margins of the leaf the 

 hypoderma consists of two rows of cells. The hypoderma is also 

 developed under the epidermis covering the prominent midrib below, 

 the layer of cells being double in the middle. The resin-canals arc 

 placed one at each side of the leaf, close to the under side, and sepa- 

 rated from the epidermis by a single layer of cells. The pallisade 

 parenchyma is well developed on the upper side, and below there is 

 parenchyma with well-marked intercellular spaces communicating with 

 the stomata. 



Fibro-vascular bundle double, the parts placed close together, and 

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

 whole is surrounded by a sheath. 



The figure (Plate 46, fig. 1) is drawn from a specimen supplied to 

 me by Mr. Syme, Elvaston Nurseries, Borrowash, Derby. 



Bertrand^ gives the following characters for A. bracteata : — 

 Olands touching the inferior epidermis ; no stomata on upper surface 

 of leaf, more than 10 rows of stomata in each band; no pseudo-liber 

 -cells in parenchyma of leaf ; zone of hypoderm continuous ; leaf mucro- 

 nate. — In the different specimens examined by me the same characters 

 were found. 



Gordonf describes this species, and directs attention to the buds, 

 while Koch| gives a description of it under the name of Pinus (Abies) 

 venusta. According to this author the name vcnusta, Douglas (1836), 

 has the priority by one year of that of bracteata, D. Don (1837). It 

 has also been described and figured by Mr. Andrew Murray, in the 

 Transactions of the Botanical Society of Edinburgh, vol. vi., p. 211, 

 with plates. Koch states that the young shoots are hairy, while Par- 

 latore says : " Eamuli glabri : " both states occur among the specimens 

 examined by me. 



P. (Abies) bracteata is one of the most distinct species of the 

 whole section. Five different specimens have been examined by me — 

 three from their natural habitats, the others cultivated. 



I am indebted to my valued correspondent, Mr. Syme, of Elvaston 

 jSTurseries, Borrowash, Derby, for a fine cultivated specimen for exami- 

 nation, a section of the leaf of this plant being the one figured. The 

 other cultivated specimen examined was from a very small plant in 

 Glasnevin Garden, kindly given to me by Dr. Moore, and in it the 

 hypoderm was not so well developed, there being 2 or 3 cells omitted 

 in 3 or 4 places, but it agreed in all other characters. 



I am indebted to Dr. Hooker, C.B., P.R. S., and to Prof. Oliver, 

 F. H. S., for permission to examine two specimens in Kew Herbarium. 

 One is a specimen collected by D. Douglas in "America boreali-occi- 



* Op. cit., p. 89. t The rinetum (18.38), p. 145. 



X Dendrologie, vol. ii., part 2, p. 210. 



