Elements of the comparative anatomy Elements of the comparative anatomy of vertebrates elementsofcompar00wied Year: 1886 PELVIC ARCH. 93 vertebra?, and corresponds to the iliac process mentioned above as being present in some Fishes; of the latter, the anterior ventral element is spoken of as the pubis, the posterior as the ischium. The articular cavity for the thigh-bone (acetabulum) is situated at the point of junction of the pelvic elements. Thus we meet here with a ground-form essentially similar to that of the pectoral arch (Fig. 71). In the pelvis of Urodela and Anura a single ventral p
Elements of the comparative anatomy Elements of the comparative anatomy of vertebrates elementsofcompar00wied Year: 1886 PELVIC ARCH. 93 vertebra?, and corresponds to the iliac process mentioned above as being present in some Fishes; of the latter, the anterior ventral element is spoken of as the pubis, the posterior as the ischium. The articular cavity for the thigh-bone (acetabulum) is situated at the point of junction of the pelvic elements. Thus we meet here with a ground-form essentially similar to that of the pectoral arch (Fig. 71). In the pelvis of Urodela and Anura a single ventral plate is seen on each side, which comes into contact with its fellow to form FIG. 77.—PELVIS OF SALAMANDEE (Salamandra maculosa). (Ventral view.) II, ilium ; Is, ischium ; P, pubis (?) (pars acetabularis ?); Fo, obturator foramen ; Sy, ischio-pubic symphysis ; t, two protuberances, present in many Urodeles ; Ep, epipubic cartilage, with its forked ends (a, b]; G, acetabulum. a symphysis (Fig. 77, Si/}, and the anterior part of which usually remains cartilaginous throughout life. It cannot, at present, be stated with certainty whether this part corresponds to the pubis, or to a fourth element, the pars acetabularis (Fig. 77, P, and 78, AV),which is present in many Amniota, inserted between the pubis and the acetabulum (comp. Fig. 83A). The posterior part, which always becomes ossified, is without doubt an ischium (Is). In some Urodeles a delicate rod of cartilage arises from the middle line of the anterior border of the pelvis, and becomes bifurcated distally (Fig. 77, Ep, a, b'). Amongst the Anura, this epipubis (' ypsiloid cartilage') is only present in Dactylethra capensis, where its form is somewhat different, reminding one of the delicate median process of the pelvis of Dipnoi (Fig. 76, c). The so-called ' marsupial bones ' of Monotremes and Marsupials have probably been developed from the representative of the epipubis. In correspondence with the mode of progression in
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