188 ANNALS OF THE ROYAL BOTANIC GARDEN, CALCUTTA. [M. amicarum 
OssERvATIONs.— The seeds of M. amicarum have a very hard albumen, of an 
ivory-like structure and colour, and are one of the sources of the vegetable ivory 
used for button making, affording a good substitute to that afforded by the seeds 
of Phytelephas. On the structure and anatomy of the vegetable ivory produced by 
Metroxylon amicarum the following works may be consulted with advantage :—F. 
Hanausek: “The Microscopy of Technical Products (1907). The Polynesian Ivory- 
nut, p. 414, f. 249." By the same author * Zeitschr. allg. Osterr. Apoth. Ver., 1880, 
XIII, 360." Idem: "Zur Anatomie der Tahitinuss. Zeitschr, Unters. Hyg., 1893, VII, 
197^ Idem: “ Realenzyklopadie d. ges. Pharm. 1 Aufl. IX., 590." 
I have based the description of the general appearance of the inflorescence on 
a sketch of the fruiting plant kindly forwarded to me by Mr. P. Nelson of the 
“Guam Agricultural Experiment Station,” but it was not stated if the plant 
perishes after fructification, as I think it must. In a note by Dr. Kersting attached 
to a specimen of the variety majus hereafter described, gathered by his collector 
Mr. Gibbon, when Dr. Kersting was General Commissioner of the Caroline, Mari- 
anne and Patan Islands, it is stated that the natives distinguish some varieties of 
the Ivory-nut Palm according to the length and breadth of the leaflets, but not 
by the form and size of the fruit. Dr. Kersting adds that he has not been able 
to distinguish such varieties. From the specimens I have been able to examine it 
has, however, appeared to me to be evident that some appreciable differences do 
exist among them, and accordingly I think that two principal varieties of M. 
amicarum may be distinguished, probably, however, connected by intermediate 
forms. In fact it is to be expected that some not perfectly identical forms of 
Ivory-nut Palm are growing in the different Islands composing the group of the 
Carolines, and that the varieties may have been once strictly localized; but now 
that this palm is planted for its nuts, certainly more than one variety may be 
encountered growing mixed in Panape. 
If the differences in the breadth of the leaflets observable between Ledermann’s 
No. 13409 and Gibbon’s No. 1189 hereafter mentioned were constant, it would 
make one credit the opinion of the natives, that some varieties of Ivory-nut Palm 
can be distinguished by the size of the leaflets. At present I think that the two 
forms recognized by me may be characterized as follows :— 
a var. COMMUNE.— Leaflets 6 cm. broad (the intermediate ones from a full grown 
piant?) Spikes (with fully developed flower buds) 22 mm. in diameter. Flowers 
8—85 mm. long, 3:5—4 mm. across. Fruit slightly broader than high, 8—9 em. in 
diameter. Seed 6'5 cm. in diameter. 
b var. MaJUs.— Leaflets (as above) 10 em. broad. Spikes (as above) 35 cm. in 
diameter. Flowers 12 mm. long, 5'6 mm. across. Fruit slightly longer than broad, 
11—13 cm. high, 10°5—12 cm. in diameter. Seed 8—3 cm. in diameter. 
As regards the given measurements of the leaflets, it has to be borne in mind 
that in herbarium specimens only a very small portion of the leaves and frequently 
only a few leaflets are available for study; that the leaves vary in size according 
to the age of the plant and on the same plant according to the place they occupy 
along the stem, and that in the same leaf the intermediate leaflets are usually larger 
than those of both ends. Generally the uppermost leaves, and, especially those 
