4  HvTCHINSON—THE MADDENI SERIES OF RHODODENDRON. 
Subseries II. — Megacalyx, with usually 10 stamens, 
always 5 ovary cells, a large calyx, and large leaves rather 
laxly lepidote, with a raised midrib on the upper surface, 
and convex petioles; the convex upper surface of the petiole 
is a splendid mark for distinguishing this group. Here again 
Bhutan is the chief centre of distribution, as it harbours four 
species, two of which extend into Sikkim, whilst Burma, Yunnan, 
and Kweichow have eacha separate species. To this group 
belong the finest species of the whole series, with very large 
scented flowers and handsome foliage. 
Subseries III.—Ciliicalyx is the largest group, made up of 
twenty-six species, which are the most troublesome to define. 
They are probably the more modern representatives of the 
series asa whole. The stamens are nearly always Io in number 
(rarely 12-13), the ovary cells very frequently 6 (rarely 5 or 7), 
a calyx (often ciliate) which becomes gradually reduced to a 
mere undulate rim, rather small leaves more or less densely 
lepidote below and frequently ciliate, with a V-shaped groove 
on the upper surface of the petiole. There is only one species 
of this subseries in Sikkim, none in Bhutan, three species in 
the Khasia Hills, one in Manipur, six in Burma, three in Siam, 
and one species common to these two countries, ten in Yunnan, 
and one in Kweichow. Subseries Czliicalyx is thus typical of 
Burma and Yunnan. 
DISTRIBUTION OF INDIVIDUAL SPECIES. 
As careful work in the discrimination of Rhododendron species 
proceeds, it becomes increasingly évident that the majority are 
very local in distribution. Only two species of our series are 
common to Sikkim and Bhutan (R. Maddeni and R. Lindley), 
the latter species also occurring in Manipur, Assam, and there 
is one species (R. Vettchianum) common to Burma and Siam, 
whilst R. crassum occurs in Western Yunnan and N.E. Burma. 
With these exceptions no species is common to any two of the 
countries mentioned above. The occurrence of R. Lindleyi in 
Sikkim, Bhutan, andin Manipur affords an interesting link 
between the Rhododendron floras of these mountainous regions. 
The more or less isolated mountain ranges of Burma, too, seem 
to possess their own particular species. Of special interest in 
this respect is Mount Victoria (10,150 ft.) in the Chin Hills, 
Western Middle Burma, where Lady Wheeler Cuffe has, within 
the last few years, collected and introduced into cultivation two 
interesting new species in R. burmanicum and R. Cuffeanum. 
In regard to Yunnan, Professor Balfour (l.c.) has already 
demonstrated in his paper on the Ivroratum series the extremely 
