. A manual of zoology. Zoology. >ou Clio IIB ATA. xiiipiiired, wliile in all other vertebrates it is paired. Most con- stant of the cartilage hones are the ethmoids (the paired ecteth- moids, ce, and the sometimes pjaired mesethmoid), and the four occipitals. On the other hand the otic and optic regions vary considerably; the otic region, from its gi'eat size, has several bones, nsnally (fig. 589) five in number: jjterotic, 7;/©, often called r ffpM pot/r. S. 7. Fjg. "iftw.—Cranium, viscera] arches, and part nf vertebral ci'lumuof Musiclua vulgaris, am antorbital process; c<i, copul
. A manual of zoology. Zoology. >ou Clio IIB ATA. xiiipiiired, wliile in all other vertebrates it is paired. Most con- stant of the cartilage hones are the ethmoids (the paired ecteth- moids, ce, and the sometimes pjaired mesethmoid), and the four occipitals. On the other hand the otic and optic regions vary considerably; the otic region, from its gi'eat size, has several bones, nsnally (fig. 589) five in number: jjterotic, 7;/©, often called r ffpM pot/r. S. 7. Fjg. "iftw.—Cranium, viscera] arches, and part nf vertebral ci'lumuof Musiclua vulgaris, am antorbital process; c<i, copula; (iji. foramen for glossopharyngeal; H, otic capsule and hyoid; Hia. hyoQjandibular; /r, iutercalare: Md, mandible (Meckel's cartilage) ; A, nasal capsule; \ ribs; ?r, trigeminus foramen ; (', vagus foraiueu; 1-s, visceral arches: 1, labial; r?, mandibular; .;, byoid: ^S. gill arches. s([uainosal; splienotic, .yjio, frequently called postfrontal; epiotic, epoj prootic, i>nj; and opisthotie, oo, tlie last sometimes lacking. In the region of the eye the cartilaginous S2)henoids are rarely well develojied, the large parasphenoid taking their phice. The same is true of the ali- and orbitfisphenoids, these sometimes form- ing an iuterorbital septum (fig. .tOO) or a more or less wide in- terorbital fenestra (fig. 58!i). The character of the visceral skeleton is related to the a(|uatic life. All fishes have numerous gill arches (five to seven, mostly five), which, since their function—gill supporting—is similar, are similar in structure. So far as they are not degenerate they con- sist each of four parts tind are connected by unjiaired t'opuhv, these often being fused. The upper ends ;ire frei(uently toothed and, in chewing, are opposed liy the rudimentary hist arch, on which accf)unt these are spoken of as the superior and inferior pharyngetil bones. The anterior visceral tirches are greatly different in car- tilaginous and bony fishes. In the former (fig. 588) the pteryg
Size: 2512px × 995px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1902
