415 



It is very probable too tbat something depends npon the quality 

 of the water. In a paper read to the British Association at 

 Brighton last August by Prof. Semper "On the normal and 

 abnormal growth of Lymn^us," it is remarked that "separated 

 individuals grow more rapidly than those remaining and reared 

 in company together," though all are reared under the same 

 conditions as regards water, food, and temperature. And it is 

 suggested "that there may exist in the water a substance, 

 probably chloride of calcium, the presence of which, at a certam 

 low per centagv, wiU determine the growth of the animal This 



is a fact not to be lost sight of by those who make a study of the 

 fresh-water shells of any particular district. 



I have thus gone over some of the chief matters for inquiry to 

 be attended to by the local Faunist, in order that his researches 

 may be available for the furtherance of modern science. It may 

 be useful to recapitulate them. In a general way, then, we want a 

 detailed account, not merely of the species of animals found ma 

 particular district, but of the varieties of each species, and this 

 especially in the class of insects. We want to know how far these 

 varieties can be traced to local circumstances, and for this purpose 

 to have them compared with others of the same species met with m 

 other places. We want a record of any changes noticed from time 

 to time in the habits and instincts of animals, especially as to how 

 far they can accommodate themselves to new conditions of life 

 forced upon them by accident; any variations in their food or 

 mode of obtaining it, or mode of defending themselves against their 



enemies. ^ t, 4.u - 



In birds, we want a register kept of their movements, whether 

 mi-ratory or otherwise, strict account being taken of the appear- 

 ance of any new species in the district, or of the disappearance of 

 old ones ; details respecting variation of plumage, especially in 

 birds of passage, as also in those species whose plumage is subject 

 to sexual or seasonal changes ; times of commencing and ceasing 

 song, with record of any variations in the note of particular 

 individuals ; any varia tions in the manner of making their nes ts, 

 • See "Athenseum," No 2340 (Aug. 31, 1872) p. 276. 



