. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ANATOMY OF VERTEBRATES. 65 arch consists of a baslhyoid and two simple ceratohyoid carti- lages ; the stylohyal is ligamentous, as in the Squatina. Short cartilaginons rays diverge from the ceratohyal to support the branchiostegal membrane, or hyoid fin. The scapular arch, which we shall find normally articulated with the occiput in osseous fishes, is attached thereto, at a little distance behind the head, by ligament and muscles in the Sharks, fig. 30, 51 : from this arch, also, cartilaginous rays, ib. h, I, immediately
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ANATOMY OF VERTEBRATES. 65 arch consists of a baslhyoid and two simple ceratohyoid carti- lages ; the stylohyal is ligamentous, as in the Squatina. Short cartilaginons rays diverge from the ceratohyal to support the branchiostegal membrane, or hyoid fin. The scapular arch, which we shall find normally articulated with the occiput in osseous fishes, is attached thereto, at a little distance behind the head, by ligament and muscles in the Sharks, fig. 30, 51 : from this arch, also, cartilaginous rays, ib. h, I, immediately diverge for the support of a radiated appendage or fin—the homotype of the tympanic or opercular fin. The capsules of the special organs of sense are all cartilaginous: that of the ear is involved in the lateral walls of the cranium ; that of the eye is articulated by a cartilaginous pedicle with the orbit; and that of the nose, figs. 30 and 63, b, is overarched by the nasal processes of the epicranial cartilage, ib. «, and is completed below by membrane. At the summit of the occiput in Carcharias and some other sharks may be seen two closely approximated oval ' fenestraj,' which lead to the acoustic labyrinth, and are covered by skin in the recent fish. Amongst the stranger forms in which special developement radiates, in diverging Irom that stage of the common vertebrate route attained by the Plagiostomes, may be noticed the lateral transverse elonga- tions of the orbital processes, supporting the eyeballs at their extremity, and giv- ing the peculiar form to the skull of certain Sharks, thence called 'Hammer- headed' (Zijrj(Bna). In the 'Saw-fish' {Pristis), the rostrum, fig. &5, is produced into a long, flat, plate, having a row of tooth-like bodies implanted in sockets along each margin. The walls of these sockets and the mldpart of the rostrum are ossified. The i^roper jaws and teeth a have the usual Inferior position in the Sharks. • In the Eagle-ray {Myliobate
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1860
