Page:The Zoologist, 4th series, vol 3 (1899).djvu/310

284 zoological. The communication by Mr. T.L. Palmer on "The Danger of introducing Noxious Animals and Birds" is well worth the most careful perusal. Some facts relating to accidental or involuntary migration may be repeated. "In November, 1895, a Central American Mouse of the genus Oryzomys, concealed in a bunch of bananas shipped from Puerto Limon, Costa Rica, was captured alive in a commission house in Washington, D.C. A young murine Opossum from Tropical America was discovered in a bunch of bananas at Ames, Iowa, during the summer of 1882, and was kept alive for some time. If such cases were frequent, it can be readily seen how a species might gain a foothold in new regions, provided the conditions were favourable for its increase." Members of the Sparrow cult will not find agreeable reading in the account of "the true character of the bird" as detailed in these pages. The expenditure for its destruction in Illinois (1891-95) and Michigan (1887-95) amounted to about 117,500 dols. The introduction of the Sky-Lark (Alauda arvensis) and the Blackbird (Turdus merula) into New Zealand, where the first has become the scourge of the turnip field, eating the seeds soon after planting, and the second is well known as a champion fruit destroyer, induces the remark that both these birds "are noted singers; but the charms of their song hardly compensate for damage to crops."

has republished a paper read at the Victoria Institute, Worcester, on "The Life of a Severn Salmon." Much has still to be learned respecting this fish, as we read that no one can give a really satisfactory statement as to the length of time a Salmon will live if it escapes death by the hands of its numerous enemies, nor can tell with accuracy the time it takes to produce a twenty-pound Salmon. We cannot say we know even the outlines of the life-history of a Salmon in fresh water. "A question of some interest arises as to the age to which a Salmon will live. Here again more evidence is wanted; a twenty-pound fish cannot be less than four years old, and is probably older. He would be hatched out, say, in 1890, would descend as a Smolt in 1891 at the earliest, and perhaps not till 1892. If he went down in 1891, he would probably return as a Grilse in 1892, as a Grilling in 1893, as a Salmon in 1894; but he might not go down till 1892, and his return in any of the stages might be prolonged, so that it will be safe to say that a twenty-pound fish is probably seven years old, and very possibly older. One fact seems clear, that the male Salmon grows larger, and so presumably lives longer than the female; it is the exception to get a female Salmon over thirty pounds, while it is common to get males over that weight. Why this is, I cannot explain; I only state the fact. Against this must be set the assertion that at spawning-time the mortality of males is said to be greater than the mortality of females."