426 NOTES AND EXHIBITS. 



filaments than in P. oceanica, the European species. Mr. 

 Maiden exhibited specimens of P. australis showing the fibre in 

 situ, and he drew attention to the possible importance the finding 

 of the Posidonia fibre may have from a geological point of view. 

 Posidonia grows at the present day on the coasts of Tasmania 

 and southern Australia as far as New South Wales; the fibres 

 are firmly attached to the plant, and it remains in doubt whether 

 or not they were washed on shore where they were found. But 

 in the absence of any available geological evidence favouring the 

 idea of raised beaches, it would be premature to conclude that 

 the finding of the fibre indicates the former existence of a sea 

 whose depth did not exceed the maximum depth in which 

 Posidonia is found growing now. 



Mr. Maiden also exhibited fruits of Davidson's Plum (David- 

 sonia pruriens P.v.M.), an edible fruit, the size of an Orleans 

 plum when fully ripe, and belonging to the Saxifragecu; it is a 

 native of Queensland, and this appeared to be the first time it 

 had ripened fruit in the Botanic Gardens, Sydney. Likewise a 

 number of New South Wales plants usually called "leafless," 

 which exhibit leaves under certain circumstances, including 

 Viminaria denudata, Bossioua scolopendria, Comesperma defoli- 

 atum, Tetratheca juncea, and Exocarpiis cupressiformis. 



Dr. Petrie showed, under the microscope, preparations of the 

 stinging hairs of the Giant Nettle-Tree (Laportea gigas). 



Mr. H. Leigh ton Kesteven read the following Note : — "Some 

 three or four years ago I collected material for a review of the 

 New South Wales Rissoidce [Mollusca]. Thanks to the courtesy 

 of workers in the other States, I was able to obtain the opinions 

 of nearly all the Australian conchologists, past and present. As 

 I do not see any immediate prospect of completing the review, 

 and as any information on this troublesome group is of value, I 

 place on record the following fragments. Rissoa petterdi Brazier, 

 recorded without definite locality from New South Wales, occurs 

 in Port Jackson. Mr. May compared my specimens with the 

 type, and was able to confirm my identification. Rissoa bicolor 



