A handbook to the cases illustrating animal locomotion / Horniman Museum and Library.

  • Horniman Museum
Date:
1912
Catalogue details

Licence: In copyright

Credit: A handbook to the cases illustrating animal locomotion / Horniman Museum and Library. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    the hind foot are nearly equal sized, and are placed close together so as to form a hook-like organ. The long tail is prehensile. Among the monkeys the spider monkey {A teles aler) is shown as being a specialised form. The arms are elongated, the first digit of the hand is absent, and the whole hand is narrow and elongated and is used in a hook-like manner, as will be observed in the specimen. The under surface of the tip of the long prehensile tail is devoid of hair, as we have seen to be the case in certain other long-tailed climbing mammals. PARACHUTING. (Cases 36 and 37.] In all parachuting animals an expansion of some portion of the body presents a large surface of resistance to the air and supports the animal for a longer or shorter period after it has launched itself into the air. The part of the body from which this expansion is formed varies, as will be explained in the following paragraphs. Most parachuting animals are also arboreal animals. This is an especially interesting point, as it seems probable that from animals which jumped from tree to tree, as does the squirrel of the present day, the para- chuting animals of the land took their origin. It is not difficult to imagine that in an animal which took these long leaps a slight lateral expansion of the side of the body arose and proved of such advantage as a parachute that it was retained and increased during evolution. Parachuting in its turn leads on to flying. VERTEBRATA—FISHES.—In the flying fish (Exoccetus evolans) the broad, elongated pectoral fins form the supporting organs when the fish is taking its aerial flights. There is considerable difference of opinion as to the method by which the fish is sustained in the air, and the matter cannot yet be regarded as definitely settled. All observers appear to be agreed that the flights are primarily taken by the fish in order to escape the pursuit of enemies in the water ; but while some think that the pectoral fins may be used as organs of true flight, though of a feebler kind than that of birds, others think that the impulse which shoots them through the air is delivered solely by the tail before leaving the water, and that the movements of the fins which have been often
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