. Text book of zoology. Zoology. 394 Vertebrata. skull are retained throughout life^ covered for the most part by membrane bones. There are two articular condyles on the occipital. The premaxillae and maxillae are closely adherent to the anterior solid portion of the skull; they are not movable as in the Teleosteans. The upper part of the mandibular arch^ the palato- quadrate, is fused to the hinder part of the skull; sometimes^ as in the Anura, it is also fused to the front part by its anterior end; it remains partly cartilaginous. In the larva there are usually, besides the mandibular and hy
. Text book of zoology. Zoology. 394 Vertebrata. skull are retained throughout life^ covered for the most part by membrane bones. There are two articular condyles on the occipital. The premaxillae and maxillae are closely adherent to the anterior solid portion of the skull; they are not movable as in the Teleosteans. The upper part of the mandibular arch^ the palato- quadrate, is fused to the hinder part of the skull; sometimes^ as in the Anura, it is also fused to the front part by its anterior end; it remains partly cartilaginous. In the larva there are usually, besides the mandibular and hyoid arches, four pairs of cartilaginous branchial arches, which degenerate to some extent in the metamorphosis; in the Urodela, the first two pairs persist. The basibranchials, tyoid, and branchial arches, are together termed the hyoid. Of the skull bones, besides those ah-eady noticed, the following must be mentioned. In the cartilaginous cranium itself there develops a pair of exoccipitals which almost completely surroimd the foramen magnum, and which bear the occipital condyles; anterior to these on either side is the petrosal, and at the front end of the cranium, the sphenethmoid. The skull is covered dorsally by a pair of nasals behind the external nares, and a pair of frentals and parietals (in the Anura those of each side fuse into a single bone); ventrally there is a parasphenoid (c/., Pish) and, anterior to this on each side, the vomer. In the palato-quadrate cartilage. 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 Boas, J. E. V. (Johan Erik Vesti), 1855-1935; Boas, J. E. V. (Johan Erik Vesti), 1855-1935. Lehrbuch der Zoologie. London, Sampson Low, Marston
Size: 1550px × 1611px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1896
