18 MR. G. D. HAVILAND: REVISION OF THE NAUCLEE®. 
only in haying but one ovule in each cell of the ovary, and in 
the fruit being indehiscent. Although the genus consists of - 
but few species it has a wide distribution. The first section of the 
genus consists of a few species allied to Cephalanthus occidentalis, 
Linn. This species stretches from Mexico and the West Indies to 
California and Canada, it is found also in Cochin China and 
Assam; it exhibits a great deal of variation, being sometimes 
glabrous and sometimes very hairy. The species allied to it are 
found growing within its area. The second section of the genus 
consists of two species found in Peru; they are almost identical 
except in the size of the flowers, and may be dimerphic forms of 
the same species. The third section of the genus consists of a 
single species found in South Africa. If the fruit of Adina 
microcephala is indehiscent, it would perhaps be more natural 
to class it under Cephalanthus. Cephalanthus is usually said to 
enter Malasia; but the evidence for this seems to rest entirely 
on a single plant, the Cephalanthus aralioides, Moritz (Zollinger, 
no. 1509), found near Tjikoyam in Java, on Aug. 21st, 1843. 
The plant was in bud only; it was dealt with several times by 
Miquel, who finally (Ann. Mus. Bot. Lugd.-Bat. iv. 183) con- 
cluded that it was Adina polycephala, and it has since been 
quoted as a svnonym for both Adina polycephala and Cepha- 
lanthus naucleoides. There is a specimen in the British Museum: 
it may very well be Adina polycephala, but it is not a Cepha- 
lanthus. 
If we compare the genus Uncaria with the genera Cepha- 
lanthus, Adina, and Nauclea, we find a curious analogy. Each 
has its greatest development in Malasia, each extends to America 
and Africa, and in each there is discontinuity between the 
Asian and African forms. Adina microcephala is analogous to 
Uncaria africana in its wide distribution and variation; both 
vary very consideraby, but in both their subdivision into distinct 
species does not seem justified. There is no Uncaria to corre- 
spond to Cephalanthus natalensis, nor to the Indian species of 
-Nauclea ; but the development of the genus Nauclea in Malasia 
closely eorresponds with the development of the genus Uncaria 
in that region, excepting that its headquarters are not in 
Malpina but further East. The most curious analogy is, how- 
ever, in South-eastern Asia, where Adina corresponds with the 
species of Uncaria which have sessile fruit and exactly similar 
