THE VICTORIAN NATURALIST. 177 



aquatic plants, Vallisneria spiralis (Linn.) and Marsilea quadri- 

 folia (Linn.) differ very much from their types according to the 

 circumstances in which they are placed; for, when growing in 

 marshy places, or where the water is shallow, they are diminutive 

 in size and have short stems. This is the case not only in the 

 Botany swamps, but also in the lagoons of the Hawkesbury. In 

 deep water, however, V. spiralis sends up its coiled peduncle for 

 several feet, and the leaf stalks of M. quadrifolia become length- 

 ened in like manner, whilst the leaves floating on the water are 

 proportionally larger. Near the coast these leaves are jjerfectly 

 smooth, but beyond the Dividing Range they become hirsute. 

 Hence some botanists have considered the plants as distinct ', 

 but Baron Mueller, from long observation and comparison of 

 specimens, has included all the Australian forms of Marsilea in 

 M. quadrifolia. The mode of fecundation in Vallisneria and the 

 reproductive organs oi Marsilea are worthy of careful investigation ; 

 for whilst the former is indicative of the wonderful ways in which 

 Nature works out her designs, the latter suggests an analogy between 

 the involucre of that genus and the carpellary leaf of flowering 

 plants (Lindley). Azollapiiinata (R. Br.) and A. rubra (R. Br.) are 

 abundant at certain seasons in our ponds and lagoons, and 

 according to the views of an eminent botanist they contain 

 evidences of the sexual system. Still lower in the vegetable 

 kingdom, but occurring less frequently, I have noticed Riccia 

 natans (Linn.) floating in ponds, but soon disappearing ; and also 

 R.fiuitans (Linn.), occasionally, in brackish water. These little 

 plants, like Lemnas and Azollas, have their part to fulfil in the 

 economy of nature, and under the microscope they present many 

 interesting features. Amongst the Naidecs, two species of 

 Tfiglochin, three of Potamogelon, and one of JVais {N. tenuifolia) are 

 common in our lagoons and rivers, but those which require a 

 more careful examination are Ifalophila, Zostera, and Posidonia. 

 H. ovalis (Hook.), or Brown's Caiilinia ovalis, seems a rare plant, 

 for I never found it but once, and that was in the river or estuary 

 near Parramatta. The leaves of my specimen were smaller than 

 those described in the " Flora Australiensis," but the general 

 character is the same. This plant grows at a considerable depth 

 below the surface of the water and therefore escapes observation. 

 In the Flora, no species oi Zoster a is given for New South Wales, 

 and in the Baron's "Census," only Z. na?ia (F. K. Mertens); but in 

 the Parramatta River, and elsewhere in New South Wales, there is 

 an abundance of a larger Zostera, which has leaves three feet long, 

 three lines broad, three nerved, with smaller nerves between them, 

 and rounded and minutely denticulate at the end. I fancy that this 

 must be Z. marina (Linn.), and like that plant it was used exten- 

 sively in the early days of the colony for bedding, packing, &:c. 

 Lower down the river, and on the shores of Port Jackson, Caulinia 



