Btctumarr? of &nimafetr $ature. 471 



column. I cannot better illustrate the pe- 

 culiar condition of the fins of this ichthyo- 

 lite, than by the webbed foot of a water-fowl. 

 The web or membrane in all the aquatic birds 

 with which we are acquainted, not only con- 

 nects, but also covers the toe_s. The web or 

 membrane in the fins of existing fishes ac- 

 complishes a similar purpose ; it both con- 

 nects and covers the supporting bones or 

 rays. Imagine, however, a webbed foot in 

 which the toes connected but not covered 

 present, as in skeletons, an upper and 

 under surface of naked bone ; and a very 

 correct idea may be formed from such a foot, 

 of the condition of fin which obtained among 

 at least one-half the ichthyolites of the Lower 

 Old Red Sandstone. The supporting bones 

 or rays seem to have been connected laterally 

 by the membrane, but on both sides they 

 presented bony and finely-enamelled sur- 

 faces. In this singular class of fish, all was 

 bone without, and all was cartilage within ; 

 and tee bone in every instance, whether in 

 the form of jaws or of plates, of scales or of 

 rays, presented an external surface of ena- 

 mel." " The Ostcolepis was cased from head 

 to tail in complete armour. The head had 

 its plaited mail, the body its scaly mail, the 

 fins their mail of parallel and jointed bars ; 

 the entire suit glittered with enamel ; and 

 every plate, bar, and scale was dotted with 

 microscopic points. Every ray had its double 

 or treble punctulated group ; the markings 

 lie as thickly in proportion to the fields they 

 cover, as the circular perforations in a lae* 

 veil ) and the effect, viewed through the 

 glass, is one of lightness and beauty." 



OSTRACEA : OSTREA. [See OTSTEE.] 



OSTR ACION. A singular genus of fishes, 

 distinguished from all others by the bony 

 crust or covering in which they are en- 

 veloped, and the species differing also from 

 each other by certain peculiarities of form. 

 They are termed Ostracions or Trunk fishes. 

 The head and body are covered with plates 

 of bone, so united as to form an inflexible 

 cuirass : leaving only the tail, fins, mouth, 

 and a small portion of the gill-opening, ca- 

 pable of motion, all of which movable 

 parts pass through openings of the armadillo- 

 like defensive coat of mail. The vertebrae 

 are also compactly fixed together. There 

 are no ventral fins, and the dorsal and anal 

 are small and placed far back. There is 

 little flesh ; but the liver is large, and abounds 

 in oil. The surface is often armed with 

 spines. Nearly all the species are natives 

 of the Indian and American seas ; and some 

 are considered excellent fish for the table. 

 None are known in the British seas. 



OSTRICH. (Struthio.) The Ostrich and 

 its allies, belonging to the order Cursores, 

 are distinguished by having their wings but 

 little developed ; and accordingly, instead 

 of being denizens of the air, they may be 

 considered as exclusively terrestrial. They 

 have wings, it is true, admirably adapted to 

 assist them in running ; but they are totally 

 incapable, by their most energetic action, of 

 raising the birds from the ground. Nor is 

 it only in the absence of perfect wings, but 



in the character of the plumage, that the 

 want of adaptation of these birds to flight in 

 the air is manifested : for the barbs of the 

 feathers have so little adhesion to each other, 

 that the air can pass readily between them. 

 It may indeed be said, that while the Ostrich 

 has the general outline and properties of a 

 bird, it still retains many of the traits of a 

 quadruped, and appears to fill up the chasm 

 in nature which separates one class of beings 

 from another. No bird, however, is more 

 justly celebrated, not only from the beauty 

 and value of its plumage, but also from its 

 great size and peculiar habits. 



The AFRICAN or THCTE OSTRICH (Struthio 

 camelus) is from seven to eight feet high from 

 the top of its head to the ground : much of 

 this, however, is made up by the great length 

 of its neck. Its head is small, and both it 

 and the neck are destitute of feathers, having 

 only a few scattered hairs. The feathers 

 on the body of the male bird are black ; but 

 on the female dusky ; those of the wings and 

 tail are white, sometimes marked with black; 

 and on each of the wings are two spurs, about 

 an inch long. The thighs are naked, and 

 the legs hard and scaly. It has two very 



large toes, of unequal size ; the largest, 

 which is on the inside, is seven inches long, 

 including the claw ; the other, about four 

 inches, is destitute of a claw. It inhabits 

 the sandy deserts of Arabia and Africa, in 

 large flocks ; everywhere avoiding the pre- 

 sence of Man, but not disliking the society 

 of other animals. The wings are furnished 

 with loose and flexible plumes. The elegance 

 of these feathers, arising from their slender 

 stems and the disunited barbs, has occasioned 

 them to be prized in all ages ; and as they 

 still constitute a valuable article of com- 

 merce, there is no chance of the Ostrich being 

 allowed to remain undisturbed, even in the 

 desolate regions which he inhabits. The 

 hunting of this bird is extremely laborious, 

 as he is far swifter than the fleetest horse. 

 The mode adopted by the Arabians and 

 Moors is to continue the pursuit as long as 



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