This third volume of the Cambridge Natural History—vols, iii. and v. having previously appeared—fully maintains the interest and character of the series. No fewer than seven contributors have assisted in the publication, which renders the task of an adequate notice somewhat difficult in our limited space.
"Flatworms and Mesozoa" have been entrusted to the pen of Mr. F.W. Gamble. Besides a fully biological treatment and a system of classification, the general zoological reader will find many of those natural history narratives to which the pages of this Journal are always open. We may instance as an example a reference to the Liver-fluke of the sheep, Distomum (Fasciola) hepaticum, which produces the disastrous disease liver-rot. This "has a distribution as wide as that of a small water-snail, Limnæa trancatula, the connection between the two being, as Thomas and Leuckart discovered, that this Snail is the intermediate host in which the earlier larval, sporocyst, and redia stages are passed through, and a vast number of immature flukes (Cercariæ) are developed. These leave the Snail and encyst upon grass, where they are eaten by the sheep. Over the whole of Europe, Northern Asia, Abyssinia, and North Africa, the Canaries, and the Faroes, the Fluke and the Snail are known to occur, and recently the former has been found in Australia and the Sandwich Islands, where a Snail, apparently a variety of Limnæa truncatula, is also found."
The Nemertines are treated by Miss L. Sheldon. These worms are common on the British coasts, and about forty species have been recorded from this area. They "are often very diversely and brilliantly coloured, the hues most commonly found being white, yellow, green, deep purple, and various shades of red and pink." There are also land and freshwater forms, in the last of which there are certainly many new genera and species to be discovered. Altogether a zoologist in want of a speciality might well take up the Nemertine worms, and he will find Miss Sheldon an excellent "coach."
Mr. A.E. Shipley, one of the editors of the Series, writes on "Threadworms and Sagitta." If these little animals are not the
