1893. NOTES AND COMMENTS. 407 



Cholera. 

 The May number of the New Review has a sensible and readable 

 article by Dr. Robson Roose on the propagation and prevention of 

 cholera. Numerous cases are cited in illustration of the intimate 

 relation between the water supply and cholera outbreaks, and hence 

 the supreme importance of the purity of water used for drinking. 

 The author does well in pointing out that dirty filters are worse than 

 none at all ; unless it is from time to time cleansed or renewed, 

 fairly good water may actually take up impurities from the filter. If 

 charcoal be the agent it should be boiled occasionally, say once a 

 month, and then dried in the sun or an oven. Spongy iron filters are 

 recommended for general use as being cheap and easily renewed. 

 The fact that water is cool and sparkling does not imply purity. An 

 outbreak in Golden Square in 1854 was traced to a well, the water 

 from which was much liked for having these characteristics, but on 

 examination was found to be contaminated by leakage and filtration 

 from a cesspool. The general rules for prevention of the epidemic 

 are those of ordinary hygiene, cleanliness in all things, moderation, and 

 care in diet and exercise. The fact that more than five-and-twenty years 

 have passed since cholera gained a footing in this country, though 

 it has from time to time reached our ports, may fairly be attributed 

 to the improved sanitary conditions which now obtain in all our large 

 towns. 



A STUDY of the range of the Molluscan genus Placostylus has lately 

 led Mr. C. Hedley to generalise in reference to the ancient geography 

 of the region of New Caledonia, the Solomon Isles, New Hebrides, 

 and Fiji Isles, and their connection with New Zealand {Proc. Linnean 

 Soc. N. S. Wales, ser. 2, vol. vii,, 1893, PP- 335~339)' ^^ thinks 

 that these islands form part of a shattered continent, never connected 

 with, or populated from, Australia, but rather deriving their fauna 

 from Papua via New Britain. The presence of genera common to 

 Australia and New Zealand is explicable on the ground that they 

 migrated, not from the one territory to the other, but each from a 

 common source, New Guinea. New Zealand and New Caledonia 

 seem to have been early separated from the northern archipelagoes 

 and to have ceased to receive overland immigrants therefrom. 

 Finally, the Fijis appear to have remained to a later date in com- 

 munication with the Solomons, though severed from that group 

 before the latter had acquired from Papua much of its present fauna. 



The problem of stocking a pond with fish receives an unex- 

 pectedly bold solution in our contemporary Illustrated Scientific B acts 

 (April 15) ; it is there said that, as the bottom of many ponds con- 

 sists of soil which was once the bottom of the sea, it probably 

 abounds in spawn deposited, say, by the fishes of the Old Red 



