. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. 64 COMPARATIVE ANATOMY ossified; while the lateral portions remain cartilaginous. In other Marsupials various stages in the reduction of the episternum are met with. Amongst the Placeiitalia the episternum is retained in the most independent condition in certain South American Cavies as well as in the Porcupine and other Rodents in which it consists of a median and two lateral parts, which are, however, quite independent of one another, and are only connected by ligaments. The median,. Fig.—48.—Pectoral Akch of Ornitho
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. 64 COMPARATIVE ANATOMY ossified; while the lateral portions remain cartilaginous. In other Marsupials various stages in the reduction of the episternum are met with. Amongst the Placeiitalia the episternum is retained in the most independent condition in certain South American Cavies as well as in the Porcupine and other Rodents in which it consists of a median and two lateral parts, which are, however, quite independent of one another, and are only connected by ligaments. The median,. Fig.—48.—Pectoral Akch of Ornithorhynchus paradoxus. , manubrium slerni ; c', c^, c^, first, second, and third ribs ; nt, sternebra ; sc, scapula ; , coraooid (Inetacoracoid) ; , epicoracoid ; cl, clavicle ; es^ nd en'-, episternum {" interolavicle"). cartilaginous portion is closely applied to the sternum, while the lateral portions are connected with the clavicles. In the Soiuromorphse and Myomorphae the episternal apparatus is still further modified, the median piece having disappeared (or more probably having united with the sternum), while the small lateral pieces are attached to the manubrium and in the SciuromorphEe articulate with the clavicles. In the Lagomorphse fibro-oartilaginous lateral portions only are present, extending as far as the clavicles. Y. THE SKULL. Iiito-odicction. The question as to the primary origin of the skull ia the Craniata has always taken a foremost place amongst the morpho- logical problems relating to the structure of Vertebrates. Until past the middle of the present century the theory which held the field was the " vertebral theory " of Goethe and Oken, according to. 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 original Wiedersheim, Robert, 1848-1923; Parker, William Newton, 1
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