The Principal forms of the skeleton and the teethHoulston & Stoneman, 1855 - 304 pàgines |
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anchylosed animal articular surface articulated attachment backwards base basisphenoid birds body bones bony calcaneum called canal canine capsule carpal cartilaginous caudal cavity cement centrum cervical character clavicle coalesced condyle confluent connate convex coracoid cranium crocodile crocodilia crown deciduous dental dentine developed diapophyses digits distal diverging appendage dorsal elements elephant enamel expanded extremity fangs femur fibula fishes fore fore-limbs frontal hæmal arch hæmal spine hæmapophyses head hoofed humerus incisors inner interspace limbs lower jaw lumbar mammalia mammals mastoid maxillary median megatherium metacarpal metatarsal modifications molar muscles nasal neural arch neural spine neurapophyses occipital osseous ossified outer pair parietal pectoral pectoral fin pelvic perforated phalanges plates posterior premaxillary premolars proportion pterygoid pulp quadrupeds ribs ridge rudimental ruminants sacral scapula segment side skeleton skull socket species sternum structure substance teeth thick tibia tissue toes tooth transverse processes true molars trunk tusks tympanic ulna upper jaw vertebræ vertical
Passatges populars
Pàgina 301 - ... as is also that tooth in the lower jaw which, in opposing it, passes in front of its crown when the mouth is closed. The...
Pàgina 186 - ... to the bottom ; if the right pectoral fin only be cut off, the fish leans to that side ; if the ventral fin on the same side be cut away, then it loses its equilibrium entirely ; if the dorsal and ventral fins be cut off, the fish reels to the right and left. When the fish dies, that is, when the fins cease to play, the belly turns upwards.
Pàgina 281 - The strength of the hyaena's jaw is such, that in attacking a dog, he begins by biting oft' his leg at a single snap. The capacity of his teeth for such an operation is sufficiently obvious from simple inspection, and had long ago attracted the attention of the early naturalists ; and, consistent with this strength of teeth and jaw, is the state of the muscles of his neck, being so full...
Pàgina 293 - ... of a Carnivore ; a transverse row of these, therefore, when the work of mastication has commenced, presents, by virtue of the different densities of their constituent substances, a series of cylindrical ridges of enamel, with as many depressions of dentine, and deeper external valleys of cement...
Pàgina 186 - ... to turn either way, a single blow with the tail the opposite way, sends it round at once : if the tail strike both ways, the motion produced by the double lash is progressive, and enables the fish to dart forwards with an astonishing velocity*.
Pàgina 198 - It is true the serpent has no limbs, yet it can outclimb the monkey, outswim the fish, outleap the jerboa, and, suddenly loosing the close coils of its crouching spiral, it can spring into the air and seize the bird upon the wing ; thus all these creatures fall its prey.
Pàgina 263 - Creator, so the modifications of the plan for the different modes of existence illustrate the beneficence of the designer. Those structures, moreover, which are at present incomprehensible, as adaptations to a special end, are made comprehensible on a higher principle, and a final purpose is gained in relation to human intelligence ; for, in the instances where the analogy of...
Pàgina 264 - ... in others as aids in locomotion, means of anchorage, instruments for uprooting or cutting down trees, or for transport and working of building materials ; they are characteristic of age and sex ; and in man they have secondary relations subservient to beauty and to speech. Teeth are always intimately related to the food and habits of the animal, and are therefore highly interesting to the physiologist : they form for the same reason important guides to the naturalist in the classification of...
Pàgina 265 - The hard substance of the tooth is thus arranged in hollow columns, perpendicular to the plane of pressure, and a certain elasticity results from these curves; they are upright where the grinding surface of the crown receives the appulse of the opposing tooth, and are horizontal where they have to resist the pressure of contiguous teeth. The tubuli...
Pàgina 226 - ... by inflating it with air ; this causes a decrease in the specific gravity of that part, and raises it to a horizontal position. The compensating power consists in the posterior half of the body becoming specifically lighter, while the specific gravity of the anterior half remains unaltered.