26 THE VICTORIAN NATURALIST. 



red rain of 1896, by several observers, but as the sediment was 

 almost invariably collected on the roofs of greenhouses or from 

 the channelings of dwellings, positions in which it was very 

 liable to contamination, it was not clearly demonstrable that 

 they had been carried and deposited by atmospheric agencies. 

 This element of doubt has been eliminated in the case of the 

 deposits under review, as they were collected in perfectly clean 

 vessels at stated intervals, and as all the glassware, chemicals, 

 and water used in the subsequent cleaning processes were 

 certainly free from similar organisms, the possibility of their 

 accidental introduction need not be entertained. 



The number and variety of these organisms is fairly consider- 

 able, though to obtain this distinction they need not, and in fact 

 do not, form any very large percentage of the total sediment. 

 Certainly it would be well within the mark to state that they do 

 not represent more than one-half per cent. Yet in a sample of 

 dried material weighing not more than 20 grains they number 

 many thousands. 



Fragments of sponge spicules, probably of Spongilla, are not 

 infrequent in most of the samples collected. 



Dried remains of the lorica of a rotifer, probably of the genus 

 Euchlanis, were occasionally met with, and the wing of an insect 

 occurred in that from Camberwell. 



The Diato:\is in the Red-Rain Sediment. 



The generic and specific forms present are in the main repre- 

 sentative of freshwater types. Species usually found only in 

 brackish water occur, but not to the same extent, while the 

 occurrence of purely marine and estuarine representatives of the 

 group is extremely rare, only one example of the former having 

 been noticed, namely, a species of Cymbosira, from the fall at 

 Camberwell. 



The number of the Diatomacese known and described is so 

 enormous, and the literature concerning them so voluminous and 

 scattered, that any attempt to enumerate all the specific forms 

 present is next to impossible to any but specialists in this group. 

 We have consequently only endeavoured to draw up a provisional 

 list of some of the more prominent species. This, of course, might 

 be greatly extended and modified by more complete examination 

 and research. 



List of DiatomacecB from lied Rain collected at St. Kilda '2Sfh 

 March, 1903. — Amphora, sp., Cymbella, sp., £ncijonema luiiula, 

 Grunow, Navicula nohilis, Ehr. (fragments), N. major, Kutz. 

 (fragments), N. lata, ^V. Smith, N. borealis, Ehr. (not quite 

 typical), N. brauniana, Grunow, JV. termes, Ehr., var. stauronei 

 Jormis, N. commutata, Grunow, JV. amhujiia, Ehr., N., sp., Stau- 

 roneis acuta, W. Smith, Stauroiitis, sp., Amphicampa mirabilis, 



