Page:The Zoologist, 4th series, vol 2 (1898).djvu/312

280 introduced into this country by Huxley, as a basis from which extended studies can be made, and the present work is stated as designed to assist those further studies. The study of types is now an excellent and almost universal method, though Prof. Ray Lankester has recently proposed that a second course might be pursued in the study of "exceptional, puzzling, and debateable animals," by which significance of structure could be considered as the means of discussing affinities.

The classification is generally in agreement with that of the recent work of Parker and Has well, but with some differences. Thus those authors appended the Nemerteans to the Phylum Platyhelminthes, whilst Prof. Sedgwick treats them as a distinct Phylum—Nemertea. He also considers the Polyzoa and Brachiopoda as constituting distinct Phylla, but which Parker and Haswell treated as classes of Molluscoida. These authors also placed the Mollusca after the Arthropoda, whilst in the work under present notice they follow the Rotifera. The position of the Echinodermata is also differently considered. We simply draw attention to the differences in method of these two notable publications because they have both appeared almost synchronously, and also because modern classifications are taken as representative of current views on derivation.

Although this text-book is necessarily of a technical description, there are still scattered some of those facts or incidents in life narratives so appreciated by the contributors and readers of this Magazine. As an instance, we may quote from the general remarks on the Mollusca. About 25,000 species are known, and are found in the sea to a depth of nearly 3000 fathoms. "Their duration of life, where known, varies from one to thirty years; the Pulmonates generally live two years, but the garden snail has been known to live five years. The oyster is adult at about five years, and lives to ten years. The Anodonta do not arrive at sexual maturity till five years, and live for twenty or thirty years."

We shall await with interest the completion of the work.