. Text book of vertebrate zoology. Vertebrates; Anatomy, Comparative. I/O MORPHOLOGY OF THE ORGANS OP VERTEBRATES. and an anterior procoracoid, both extending inwards; and fre- quently the inner ends of these are united b}' a longitudinal cartilaginous band, — the epicoracoid. To these may be added a clavicle, developed from membrane, in front of the proco- racoid, extending in- wards from the scap- ula, and usually con- necting with the sternum by means of the episternum. These parts undergo various modifications, and some or all of them, with the excep- tion of the scapula, may, here and the
. Text book of vertebrate zoology. Vertebrates; Anatomy, Comparative. I/O MORPHOLOGY OF THE ORGANS OP VERTEBRATES. and an anterior procoracoid, both extending inwards; and fre- quently the inner ends of these are united b}' a longitudinal cartilaginous band, — the epicoracoid. To these may be added a clavicle, developed from membrane, in front of the proco- racoid, extending in- wards from the scap- ula, and usually con- necting with the sternum by means of the episternum. These parts undergo various modifications, and some or all of them, with the excep- tion of the scapula, may, here and there, more or less com- p 1 e t e 1 y disappear. Possibly the most common is the re- placement of the procoracoid b\" the clavicle. The details of these modifications be given in connection with the groups in which they occur; but in the majority the two halves of the pectoral girdle are more or less firmly united by means of the sternum. The pelvic girdle presents many similarities to the anterior arch. In the elasmobranchs there is the same transverse arch as in the shoulder girdle ; and this supports the ventral fins, there being in some cases a dorsal portion beyond the fossa (acetabulum) in which the fin articulates. There thus arise a dorsal iliac portion and a ventral ischio-pubic portion in each half of the arch, the ventral part being perforated b\- an opening (obturator foramen) for the obturator nerve. In the other fishes the pelvic girdle is much less developed, and in the teleosts the fins are supported by these enlarged basal elements (vide infra). In the amphibia and higher groups the iliac por-. FiG. 182. C, clavicle ; Shoulder girdle of Ornithorhynchtis. CO, coracoid; E, episternum; EC, epicoracoid; S, scapula; ST, sternum; R, ribs. will. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the origi
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