an illustration the Arthropoda are subdivided into (1) Crustacea, (2) Onychophora—Peripatus only, (3) Myriapoda, (4) Insecta, (5) Arachnida. Each group is represented by an individual, of which a complete and exhaustive examination is made, so that a series of analytical types afford a clear insight into the real inwardness of the classification. Thus Brachionus rubens is made a representative of the Rotifera, and a Cockroach (Periplaneta americana) is used to focus the structure of the Insecta; and in this way if the student is unable to obtain the identical species for examination, an allied form will easily be procurable, and will serve a similar purpose. In Aves, which form Class V.[1] of the phylum Chordata, the Common Pigeon (Columba livia var. domesticata), is chosen as the subject for demonstration. The whole class is divided into two subclasses—Archæornithes (Mesozoic birds) and Neornithes. The last form two divisions: Ratitæ—flightless Neornithes, including Emus, Cassowaries, Rheas, Ostriches, &c.—and Carinatæ, in which, "with the exception of some flightless species, the sternum has a keel," &c. The classification thus runs from the Emus, Cassowaries, Moas, Ostriches, and allied forms now extinct and in the domain of palæontology, through the Divers, Petrels, Herons, Ducks, and Geese, when we reach the Accipitres. Then follow Gallinæ, Grallæ, Gaviæ, Limicolæ, Pterocletes, Columbæ, Psittaci, and we arrive at the Owls (Striges). After these Picariæ, when the system ends with the Passeres. Whatever may be the opinion of ornithologists as to this arrangement, they will doubtless agree with the authors that—"In respect of range of structural variations, the entire class of Birds is hardly the equivalent of a single order of Reptiles. Among existing Birds the Emu and the Raven, which may be said to stand at opposite ends of the series, present nothing like the anatomical differences to be found between a common Lizard and a Chameleon, or between a Turtle and a Tortoise."
The chapters at the close of the second volume are devoted to those topics which interest all zoologists, and prove a charm to most readers. On the subject of "Distribution" excellent point is made by the comparison of the faunas of Great Britain and New Zealand. These two insular areas are not widely different in size, have each a temperate climate, a physiography of considerable
- ↑ In error styled Class VI. in text, vol. ii. p. 350.
