GENERA OF TAXACEE AND CONIFERE. 19 
generally two to each scale, and in the circumstance that the 
cones ripen in one season. 
Thuyopsis, so far as the Japanese and the North-west Ameri- 
can species are concerned, is also referable to this genus. 
Retinospora has no claim to generic distinction, the so-called 
species being merely phases of growth of certain species of 
Cupressus, Thuya, or Juniperus. Ferd. von Mueller, in his ‘ Select 
Plants for industrial culture,’ correctly referred the Retinosporas 
to Cupressus. 
The species are natives of the Levant, the Himalayas, China, 
Japan, North-western and North-eastern America, and Mexico. 
Two species of Cupressus occur in a fossil state, the one in the 
Lower Eocene of Ireland, the other in the Middle and Upper 
Bagshot beds according to Starkie Gardner. 
THUYA. 
A generic name adopted by Linneus in 1737 from Tournefort 
(1700) and older writers, the thyon of the Greeks being probably 
the plant here called Tetraclinis articulata. As here understood, 
the genus T’huya comprises the sections Euthuya, Macrothuya, 
and Biota of Bentham and Hooker. It is characterized by its 
flattened branchlets usually in one horizontal plane, the presence 
of dimorphic foliage, moncecious flowers, decussate stamens, 
3-4 anther-cells, simple pollen ; female cones solitary at the ends 
of the branches, ultimately pendulous (except in Biota), oblong 
or ovoid, rarely globose, ripening in the first year ; the 4-6 scales 
decussate, slightly imbricate, oblong, acute, not peltately ex- 
panded as in Cupressus, the central ones fertile, or (in Biota) 
the lower ones. Thuiopsis dolabrata of Siebold and Zuccarini 
and 7. borealis of Carriére belong more properly to Cupressus ; 
whilst Thuiopsis Standishii is a true Thuya and the Japanese 
representative of the North-west American 7. gigantea. The 
species occur in the Levant, the Himalayas, China, Japan, North- 
east and North-west America, and were widely distributed in 
both hemispheres in Miocene and Secondary times. See Brown 
of Campster, ‘Monograph of Thuya.’ 
LiBoceDRUs. 
A genus founded by Endlicher in 1847, and admitted by 
subsequent writers under the same name or in the form of a 
synonym, such as Heyderia, Karl Koch (Dendrologie, ii. 172), 
c 2 
