Page:A Voyage to Terra Australis Volume 2.djvu/626

612 Azolla fronde circumscriptione triangulari pinnate et semibipinnata: foliolis superioribus papulosis, radicibus longitudinaliter plumosis. ''Prodr. fl. nov. holl.'' 167.

In lakes and ponds, frequent within the limits of the colony of Port Jackson.

DESC. Plantula natans, facie Jungermanniæ. Radices axillares solitariæ perpendicalares hyalinæ, primo aspectu simplicissimæ, per lentem plumosæ, novellæ calyptra glabra subulate tectæ. Frons semuncialis: Ramis distichis alternis approximatis parallelis teretiusculis; intimis haud rarò pinnatis; superioribus sæpe instructis gemmulis ramulorum nonnullis axillaribus teretibus. Folia alterna undique imbricata: in latere superiore frondis trapezoideo-ovata, crassiuscula cellulosa, viridia passim rubicunda, margine exteriore submembranaceo, supra convexiuscula papuloso-scabra, subtus lævia: in latere inferiore tenuiora lævia, subconformia vix tamen angulata. Perichætia in superficie inferiore frondis, prope basin pinnæ solitaria.

Obs. Mr. Bauer's very satisfactory figure and the generic character already given, will in a great measure supersede any farther description of the singular structure of this genus; on which, however, it appears necessary to subjoin a few remarks.

Admitting the parts of fructification to be accurately described, it is not easy to understand in what manner the male influence is communicated to the female organ. In one instance the turbid fluid, which usually fills the cavity of the lower cell of the supposed male organ, was found converted into a powder, and it is not improbable that this change ultimately takes place in all cases where the organ attains perfection. This powder may be supposed either to be discharged by the lateral rupture of the double coat of the containing cell, or a communication may at length be opened between this cell and the tubular axis of the upper cell, which, after the separation of its outer membrane, is open at the top; in this case the ejection of the pollen, or even of a fluid matter, may possibly be aided by the pressure or action of the angular solid bodies which surround this axis, and its dispersion would, no doubt, be assisted by the increased surface of its divided apex.

But whatever supposition may be formed respecting the œconomy of this part, it appears to me that as it is found in a second species of the genus, and of essentially the same structure, though slightly modified, the angular