. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. 126 COMPARATIVE ANATOMY tremities, the anterior undergoing the most varied adaptative modifications, and giving rise to tactile, prehensile, or flying organs —or, as in aquatic Mammals, becoming once more converted into rowing organs. The limbs of all the higher Vertebrata may, how- ever, also be reduced to a single ground-type. The fore- and hind-limbs show a great similarity as regards the form and position of their various parts. A division into four principal sec- tions can always be recognised: in the case of the
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. 126 COMPARATIVE ANATOMY tremities, the anterior undergoing the most varied adaptative modifications, and giving rise to tactile, prehensile, or flying organs —or, as in aquatic Mammals, becoming once more converted into rowing organs. The limbs of all the higher Vertebrata may, how- ever, also be reduced to a single ground-type. The fore- and hind-limbs show a great similarity as regards the form and position of their various parts. A division into four principal sec- tions can always be recognised: in the case of the fore-limb these are spoken of as upper arm (brach- ium), fore-arm (antibrachium), wrist (carpus), and hand (manus); and in the hind-limb as thigh (femur), shank (cms), ankle (tarsus), and foot (pes) (Figs. 105, 106). The bone of the upper arm (humerus) and of the thigh (femur) is always unpaired, but two bones are present in the fore-arm and shank. The former are called radius and ulna, and the latter tibia and fibula. The hand and foot are also respec- tively divisible into two sections, a proximal metacarjnis and metatarsus, and a distal series of phalanges, which form the skeleton of the fingers and toes (digits). Both manus and pes are made up of several series of cylindrical bones. There are never more than five complete series, which—except as regards number—present essen- tially similar primary relations throughout the higher Vertebrates. The skeleton of the carpus and tarsus, each of which always consists of a series of small cartilages or bones, shows much variation; but the following may be taken as a ground-type (Figs. 105 and 106). Round a centrale, which may be double, is arranged a series of other elements, of which three are proximal, and a varying number (four to six) distal. The proximal, in correspondence with their relations to the bones of the fore-arm and shank respectively, are spoken of as radiale or tibiak, idnare or Jibulare, and intermedium; whil
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
