MR. G. D. HAVILAND: REVISION OF THE NAUCLEEXR. 11 
they are smaller, and then are generally found growing on the 
banks of rivers, above the tidal limits. 
Species of the Tribe are scattered over almost all the warmer 
regions of the earth, but they are most numerous in Malasia. 
CLASSIFICATION AND DISTRIBUTION. 
In arranging the species of this Tribe into natural groups, the 
genus Uncaria forms the most marked one. Whether its climb- 
ing habit and the long 4-angled internodes of the branchlets, or 
whether the solitary axillary peduncles, often converted into 
recurved and flattened hooks, or whether the linear placentas 
centrally attached with ovules, all imbricating upwards, and the 
fruit-capsules opening at the sides, with filamentous seeds, be 
considered, there is no difficulty whatever in distinguishing the 
species of Uncaria from those of other genera. Whilst, how- 
ever, in the other species the character of the stigma is of 
generic value, in Uncaria various forms of stigma may be found. 
In the other groups too the presence of interfloral bracteoles is 
a generic character, but in Uncaria they may be present or 
absent: in the Asian species they are present in those whose 
fruit-capsules are sessile, and absent in those whose fruit- 
capsules are pedicelled, and these characters subdivide the 
genus in a natural way as far as the Asian and Malayan species 
are concerned ; but the two American species, whilst they have 
interfloral bracteoles, have their capsules pedicelled. We can 
arrange the genus naturally into six groups: those without 
interfloral setæ will have four, one African and three Malayan; 
those with interfloral sete will have two, one Asian and one 
American. 
The genus Uncaria has the widest distribution; its species 
are most numerous in Malasia, and especially so in Malpina- 
Looking to the South-east, New Guinea, Australia, and the 
South Sea Islands, we find very little: Uncaria pedicellata has 
reached New Guinea, Uncaria appendiculata, which might easily 
rank as a marked variety of U. ferrea, has reached New Guinea, 
Australia, and the Solomon Islands; but these forms have 
changed so little that they must have migrated from Malasia at 
quite a recent date ; only one peculiar species (U. Bernaysii) is 
known from New Guinea. Looking to the Northward, we find 
the Malayan forms which have pedicelled fruit and no inter- 
floral bracteoles replaced on the Asian continent by species with 
