164 Pro ceedings . 



appears, therefore, that no considerable alteration takes place in the density of 

 gold and copper when combined. I do not, however, overlook the circumstance 

 that the usefulness of this is iaterfered with by a doubt as to the exact proportion 

 of copper in the coin ; which I believe in different sovereigns varies within certain 

 limits, the limit of faUibUity for fineness being l-16th of a carat. 



Eeturning to the value of New Zealand gold, it is estimated from the above 

 experiments, that an ounce entirely free from quartz or other substance except 

 silver is worth £3 8s. lOd. ; (that of pure gold being 2.1237c^. per grain, and that of 

 pure silver, 'ISeT^i. per grain, as found by Yoiu* Excellency.) 



Trusting that Tour Excellency will overlook the liberty I have taken in address- 

 ing you, 



I am, &c., 



Chaeles Knight. 



"His Excellency Sir W. T. Denison, F.R.S." 



Mr. MiUigan placed on the table ripe capsules of the Blue gum, recently col- 

 lected by him in the vicinity of the Apsley River, in the Swanport disti-ict. Mr. 

 Swainson said that he recognized amongst them sis distinct species of his proposed 

 new genus Denisonia ; two of which, he says, differ specifically from any pre- 

 viously seen by him. 



Mr. MUligan also exhibited a curious dwarf specimen of she-oak (Casuarina,) not 

 quite a foot high, bearing a cluster of full-sized, monstrous, abortive cones. This 

 led to an interesting conversation on the influence of temperature, &c., on the 

 forms, characters, and geographic distribution of plants and animals, in which 

 His Excellency Sir "WiUiam Denison, Drs. Agnew and Crooke, Mr. Walker, and 

 others joined, when Mr. Swainson took occasion to express his conviction that 

 " there exists a wide and marked difference between the trees of Tasmania and 

 those of "Victoria, notwithstanding the positive assertions to the contrary published 

 in the recent report of the Victorian Colonial Botanist." In proof of this, Mr. 

 Swainson stated that " out of more than sixty (!) different species of Casuarinae dis- 

 covered, drawn, and described by biTn during his short residence in this island, he 

 has not met with one which is also a native of Victoria ;" and adds, that " more 

 than one-half of those discovered by him at Launceston are totally difierent from 

 those met with at the southern end of the island." 



Mr. Swainson remarked " that this diversity is equally conspicuous among the 

 Gum. trees, only two out of more than forty species detected in Tasmania being 

 considered by him as common to the opposite coasts of Bass's Strait — ^whUe of the 

 genuine Blue gums, so common on the southern and eastern pai'ts of Tasmania, 

 not one has been observed by Mr. S. in the province of Victoria: one, indeed, he 

 says, has been recently said to have been found growing near Cape Otway, on the 

 coast of Victoria ; but he thinks the fact requires verification." 



A paper embodying descriptions, and accompanied with beautihiHy executed 

 figures by Mr. Swainson, of some undescribed Trochiform shells of Tasmanian seas, 

 now in Mr. MiUigan's collection, was then read : — One closely resembling CalUo- 

 stoma in its colouring, perlacious structm-e, and elevated apes, and Solarium in its 



