COMl'ARATlVi: \IKW. 1G9
advanced, but yet in a state of considerable development, indicated either by the entire want or scanty remains of albumen : the only exception to this being Lean, in which the embryo is many times exceeded in size by the albumen.
In the Monocotyledonous plants, on the other hand, con- sisting of Graminca?, Cyperacea), Gloriosa, Elagellaria and Pistia, the embryo bears a very small proportion to the mass of the seed, which is formed of albumen, generally fannaccous. But it may here be observed that the existence of a copious albumen in Monocotyledones does not equally imply an inferior degree of vitality in the embryo, but [482 may be considered as the natural structure of that primary division ; seeds without albumen occurring only in certain genera of the paradoxical Aroidese, and in some other Monocotyledonous orders which are chiefly aquatic.
5th. Doubts may be entertained of the identity of particu- lar species. On this subject I may observe, that for what- ever errors may be detected in these lists, I must be considered as solely responsible ; the insertion of every plant contained in them being founded on a comparison of specimens from the various regions of which their existence in the particular lists implies them to be natives. The only exception to this being Lipocarpha argentea, of which I have not seen American specimens ; as a native of that continent therefore it rests on the very sufficient authority of Baron Humboldt and M. Kunth.
Tn my remarks on the natural orders, I have already suggested doubts with respect to certain species included in the lists, and shall here add a few observations on such of the others as seem to require it.
Acrosticlum aureum, L. was compared, and judged to agree, with American specimens ; and I have therefore placed it in the 2nd list, without, however, meaning to decide whether those plants originally coml)ined with A. aureum, and now separated from it, should be regarded as species or varieties.
Faircna umbellala, Z. //. from Congo, has its umbels somewhat less divided than either the American plant or that from the continent of India ; but from specimens
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