6 



ANIMAL LOCOMOTION. 



tiori must possess those peculiarities of structure which charac- 

 terize, as a class, those animals which live on the land, in 

 the water, or in the air respectively. 



In this we have an explanation of the gossamer wing of 

 the insect, — the curiously modified hand of the bat and bird, 

 — the webbed hands and feet of the Otter, Ornithorhynchus, 

 Seal, and Walrus, — the expanded tail of the Whale, Porpoise^ 

 Dugong, and Manatee, — the feet of the Ostrich, Apteryx, and 

 Dodo, exclusively designed for running,— the feet of the 

 Ducks, Gulls, and Petrels, specially adapted for swimming, — 

 and the wings and feet of the Penguins, Auks, and Guille- 

 mots, especially designed for diving. Other and intermediate 

 modifications occur in the Flying-fish, Flying Lizard, and 

 Flying Squirrel ; and some animals, as the Frog, Newt, and 

 several of the aquatic insects (the Ephemera or May-fly for 

 example-^) which begin their career by swimming, come 

 ultimately to walk, leap, and even fly.^ 



Every degree and variety of motion, which is peculiar to 

 the land, and to the water- and air-navigating animals as such, 

 is imitated by others which take to the elements in question 

 secondarily or at intervals. 



Of all animal movements, flight is indisputably the finest. 

 It may be regarded as the poetry of motion. The fact that 

 a creature as heavy, bulk for bulk, as many solid substances, 

 can by the unaided movements of its wings urge itself through 



1 The Ephemerae in the larva and pupa state reside in the water concealed 

 during the day under stones or in horizontal burrows which they form in the 

 banks. Although resembling the perfect insect in several respects, they differ 

 materially in having longer antennae, in wanting ocelli, and in possessing 

 horn-like mandibles; the abdomen has, moreover, on each side a row of 

 plates, mostly in pairs, which are a kind of false branchiae, and which are 

 employed not only in respiration, hut also as jgaddUs. — Cuvier*s Animal 

 Kingdom, p. 576. London, 1840. 



2 Kirby and Spence observe that some insects which are not naturally 

 aquatic, do, nevertheless, swim very well if they fall into the water. They 

 instance a kind of grasshopper {Acrydium), which can paddle itself across a 

 stream with great rapidity by the powerful strokes of its hind legs.— (Intro- 

 duction to Entomology, 5th edit., 1828, p.. 360.) Nor should the remarkable 

 discovery by Sir John Lubbock of a swimming insect (Polynema natans), 

 which uses its wings exclusively as fins, be overlooked.-— Linn. Trans, vol. 

 xxiv. p. 135. 



