MR. J. MIERS ON THE HIPPOCRATEACEX OF SOUTH AMERICA. 829 
gaping a little at the summit: it contains about eighty seeds, attached to the sides of 
the dissepiment, horizontally imbricated, and closely packed together in ten superposed 
series of four each; the seed is scobiform, oblong, compressed, containing in the centre 
an embryo of half its length, surrounded by and enclosed within a lax reticulated testa. 
This embryo is oblong, white, fleshy, consisting of two oblong cotyledons and a sub- 
conical radicle of half their length, which points to the hilar point of attachment of the 
seed. From this description, it is evident that Alzatea cannot belong either to the 
Celastraceæ or Hippocrateacee. DeCandolle, in 1824, first placed the genus in Celas- 
trace? ; and botanists have since followed this example for want of a better knowledge 
of its structure. In 1845, Dr. Planchon, in a memoir* on the affinities of the genera 
Crypteronia, Bl. (Henslovia, Wall.), Raleighia, Gardn., and Alzatea, R. &. P., considered 
them all to be intimately related, their position being among the Zythraceæ ; and accord- 
ingly he placed Raleighia next to Abatia; but both these genera have since been trans- 
ferred to Samydacee: it is, however, certain that neither Crypteronia nor Alzate 
belong there. Including, perhaps, Zetrataxis, they appear to me to constitute a peculiar 
group, the chief characters of which consist in the position of the stamens, alternate 
with the sepals, outside of a compressed disk; in the absence of petals; in the superior 
2—4-celled ovary, with numerous ovules; in a capsule surrounded by the persistent 
sepals, 2- or more-celled, with numerous scobiform minute seeds, having a reticulated 
testa and an albuminous embryo, with the radicle pointing to the hilum. It appears 
desirable to place them for the present as a tribe (Crypteroniee) attached to Rhamnacee, 
with which family they accord in some respects, especially in the position of the 
stamens. 
. My observations on Ptelidiwm may also be noticed. This genus was established by 
Thouars in 1806, on a Madagascar plant t, and has hitherto been placed in Celastracee 
(but erroneously so, as it appears to me), on account of its extrorse stamens placed within 
an hypogynous disk. This genus was examined not long since by M. Tulasne 1, whose 
description accords with the account of Thouars in most respects: it has four sepals, four 
alternate petals, four stamens with extrorse anthers, situated between an elevated free 
disk aud the ovary, as in Hippocrateacee. The fruit is broadly obcordate, extremely 
compressed, with a very dilated coriaceous winglike margin, and an indehiscent osseous 
endocarp, also compressed, 2-celled, with an erect exarillate seed fixed in the bottom of 
each cell. M. Tulasne, unfortunately, was not able, from the decayed state of the seeds, 
either to confirm or to refute the statement of Thouars, which appears to me a very 
doubtful one, that it possesses an embryo placed in the middle of albumen. In the hope 
of ascertaining this point, I was permitted to examine the single fruit existing in the 
British Museum, which agrees well in shape and size with Poiret's drawing $, but was 
unsuccessful, because both cells were completely void of the smallest trace of a seed, 
though a small black spot was discernible in the bottom of each cell. From this we may 
infer that the ovules were never fertilized, but that, notwithstanding this, the fruit and 
* Lond. Journ. Bot. iv. p. 474. + Gen. Nov. Mad. p. 24; Hist. Veg. p. 25, tab. 24. 
t Ann. Sc. Nat. 4* sér. viii, 104, $ Lam. Ilust. tab. 916. 
