. Elementary text-book of zoology. 336 CHORD AT A. ring posteriorly, consisting of a supraoccipital, paired exoccifitals and a basioccipital; (2) the otic bones suri-ouriding the auditory capsule and lying, immediately in front of the occipitals. There are five otic bones—prootic, epiotic, opisthotic, pterotic and sphenotic. On the two last is a large facet for the hyomandibiilar bone. (3) At the front end of the cranium are a series of bones arising in connection with the nasal capsules, the dorsal nasals, median mesethmoid and lateral (4) Between these and the occipital and aud
. Elementary text-book of zoology. 336 CHORD AT A. ring posteriorly, consisting of a supraoccipital, paired exoccifitals and a basioccipital; (2) the otic bones suri-ouriding the auditory capsule and lying, immediately in front of the occipitals. There are five otic bones—prootic, epiotic, opisthotic, pterotic and sphenotic. On the two last is a large facet for the hyomandibiilar bone. (3) At the front end of the cranium are a series of bones arising in connection with the nasal capsules, the dorsal nasals, median mesethmoid and lateral (4) Between these and the occipital and auditory region the dorsal surface of the cranium is completed by small parietals in front of the supra- occipital and large frontals covering the orbits. In front of the otic bones there is a pair of small alisphenoids in the orbit. (5) The basal axis of the cranium is formed, anteriorly to the basioccipital, by the long parasphenoid and vomer, the latter bearing teeth and lying below Fig. 238.—The Right Pectoral Fin and Girdle of the Cod WITH BOTH Pelvic Fins. {Adfiai.) Post-temporal. ,. iipterygiunu Dermal Fin-rays. Distal Pterygiophores. Proximal Ptery^ophores (Brachial Ossicles). Fin-rays. ^ the mesethmoid. (6) Lastly, in connection with the orbit is a chain of orbital bones, of which the anterior and largest is known as the lacrymal. To this cranium are loosely attached a number of bones belonging to visceral arches. Anteriorly are paired premaxillcs bearing teeth, and maxilla without teeth. These are supposed to be connected with the labial cartil^es of the skate. The first or mandibular arch ossifies into the palatines attached to the ectethmoids, the pterygoids with meso- and metapterygoids, and the guadrates which form the upper half (or palatoquadrate chain) and the articular, angular and dentary forming the lower half or mandible. An articulation is formed between the articular and the quadrate. The second or hyoid arch consists in its upper half of a
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