70 INTRODUCTION. 



by the white in the oviduct, and at the bottom of the same 

 canal receives its shell. The heat of the weather, or more 

 commonly, maternal incubation, develops the young. 



OF THE VIVIPAROUS VERTEBRATED ANIMALS. 



61. Viviparous vertebrata, or mammalia, among which is 

 man, differ from the ovipari, not only in their mode of genera- 

 tion and in their quantum of respiration, but are particularly 

 distinguished by the most perfect animal functions, and a 

 greater intelligence, less under the domination of instinct, 

 and more capable of perfectiveness. 



Their general conformation is that of the vertebrata. The 

 splanchnic cavity of the trunk is divided by a complete muscu- 

 lar partition called the diaphragm. With one single exception, 

 they have seven vertebrae in the neck; they have a sternum to 

 which the first ribs are attached. The head is always articu- 

 lated with the first vertebra by two condyles. The cranium 

 is very similar in its composition. The occipital, sphenoidal, 

 ethmoidal, parietal, frontal and temporal bones, always exist; 

 in the foetus several of these bones consist of different pieces. 

 The face also has but little variety; it is essentially composed 

 of the superior maxilla, the inter-maxillary bones, the ossa pa- 

 lati, the vomer, the bones of the nose, the inferior ossa turbi- 

 nata, and of the jugal and lacrymal bones: these united form 

 the upper jaw which is fixed to the cranium: the lower one, 

 formed of two pieces, is articulated by projecting condyles to 

 fixed temporal bones. An os hyoides, suspended to the cra- 

 nium by ligaments, supports the tongue, which is always fleshy. 

 The anterior or superior members originate from a bony cinc- 

 ture or shoulder, formed by the scapula, not articulated with 

 the spine, supported in many of the mammalia by the sternum, 

 by means of a clavicle. The arm is formed of one single bone ; 

 the fore-arm of two, the radius and ulna; the hand which ter- 

 minates these limbs, is composed of two ranges of small bones 

 called the carpus, of a range of bones called metacarpus, and of 

 fingers, each of which consists of three bones called phalanges. 

 The posterior or lower limbs are similarly formed, and this 



