British Museum (Natural History) General Guide

by British Museum

Bay No. III is devoted to the class of Birds. An Albatross (Diomedea exulans) mounted with the wings expanded shows the most important characters by which a Bird is externally distinguished from other animals. The body is clothed with feathers, which (in the majority of Birds), by their great size and special arrangement upon the fore-limbs, enable these to act as organs of flight. The mouth is in the form of a horny beak. A nestling Albatross shows that at this stage of its existence the bird is not clothed with ordinary feathers, but with soft down, which serves to keep the body warm, although it confers no power of flight. An Emu and an Apteryx in the lower compartment of the case display the exceptional condition (found only in a comparatively few members of the class) of Birds with wings so small as to be concealed beneath the general feathery covering of the body, and quite useless. In the Penguins, of which two species are shown in the case, the wings are reduced to the condition of fins, and are serviceable only for progress through water.

In the first wall-case the principal features of the skeleton of the class are shown. Sections of bones exhibit the large air-cavities within; a complete skeleton of an Eagle, with the bones separated and named, and mounted skeletons of the Ostrich, Penguin, Pelican, Vulture, Night-Parrot, Fowl, etc., show the chief modifications of the skeleton. The Apteryx possesses the smallest, and the Frigate-bird the longest bones of the wing, the correspondence of which can be readily traced by means of the labels attached to them. The under surfaces of the skulls of various birds are shown with the different bones coloured to indicate their limits and relations; these are followed by a series of the different types of sternum or breast-bone.

The second wall-case contains further illustrations of the anatomy of Birds. In the left-hand part a series of wings of Birds displays the form characteristic of different groups; while above them are a few of the different types of tails, supplementing the series of tails in the table-case. Very instructive is a series of skins of white chickens of the same brood at different ages, displaying the gradual replacement of the down by the adult plumage.

The table-case in the middle of the bay contains illustrations of the external characters, the beak, the feathers, and the tail, as well as of the fore and hind limbs, or wings and feet. By the aid of the explanatory labels, the essential characters and the principal modifications of all these parts may easily be followed.

Two cases on the wall in the vestibule leading to the Fish Gallery illustrate the chief modifications of the eggs of Birds, and their differences in structure, number, form, size, texture of surface, and colour. On the side of the main staircase opposite are specimens illustrating the parasitic nesting habits of certain Cuckoos and various other Birds; while near by is a remarkably fine series of the eggs of Cuckoos with those of the Birds among which they were respectively deposited. On the opposite (east) side of the staircase the visitor will find a case showing the remarkable variation in colouring and markings displayed by the eggs of the Guillemot.

Bay IV. General structure of Reptiles and Amphibians.

The fourth bay on the west side of the hall exhibits the leading peculiarities in the structure of Reptiles and Amphibians. Owing to the large number of groups in the former class now extinct, many fossil specimens, or plaster reproductions of the same, are shown. The wall-case on the south side of this bay illustrates the different ordinal groups of Reptiles—living and extinct. Very instructive are the skeletons of Tortoises and Turtles, showing the relations of the vertebræ and limb-bones to the bony part of the shell. Lizards and Snakes are mostly represented by coloured casts. The extinct Dinosaurs are represented by a small-sized model of Iguanodon, together with a photograph of the skeleton and a plaster-cast of the bones of the hind-foot showing the three toes.

The adjacent side of the table-case shows the modifications of the backbone, or vertebral column, of the ribs, and of the limbs, in the different groups of the class. Specially noticeable are examples of five types of Skink-like Lizards, exhibiting the gradual diminution in the size of the limbs and their final disappearance.

The opposite, or north, side of the table-case displays the different modifications of the skull and teeth of living and extinct Reptiles. In some, like Crocodiles and Ichthyosaurs, the jaws are armed with a full series of sharply pointed teeth, while in others, like the Tortoises and Turtles, they are devoid of teeth and encased in horn. Very remarkable is the approximation to a carnivorous mammalian type presented by the dentition of some of the extinct mammal-like Reptiles, or Theromorphs, and equally noticeable are the palatal crushing teeth of certain other extinct Reptiles known as Placodus and Cyamodus. The peculiar dentition of the New Zealand Tuatera, and likewise that of its extinct European and Indian ally Hyperodapedon ([fig. 9]), are also shown.