. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. THE SKULL 73 or parasitic (Myxine) mode of life of these animals : the most important of these is the absence of jatus such as are present in all other Craniata; for this reason these forms are spoken of as Gyclostomata to distinguish them from the other craniate Verte- brates or G-nathostomata. Instead of the jaw-apparatus, which has doubtless become degenerated, and indications of which as well as of the hyoid can apparently still be seen (Fig. 54, , p. , , ), a number of cartilages are present s
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. THE SKULL 73 or parasitic (Myxine) mode of life of these animals : the most important of these is the absence of jatus such as are present in all other Craniata; for this reason these forms are spoken of as Gyclostomata to distinguish them from the other craniate Verte- brates or G-nathostomata. Instead of the jaw-apparatus, which has doubtless become degenerated, and indications of which as well as of the hyoid can apparently still be seen (Fig. 54, , p. , , ), a number of cartilages are present supporting the anterior part of the head. In the adult Lamprey, for instance, the suctorial mouth is supported by various skeletal elements, amongst which may be mentioned a ring-like cartilage around the margin of the dome-shaped oral funnel, between the dorsal side brb 1 Its 335in ^ncli. Fig. 54.—Skull with Branchial Basket of Petromyzon marinns. (After W. K. Parker.) The cartilaginous parts are dotted. anterior dorsal cartilage ; anterior lateral cartilage; annular cartilage; auditory capsule; 1—~, vertical bars of branchial basket; 1—7, external branchial clefts; cornual cartilage; cranial roof; he. 1—4. longitudinal bars of branchial basket; lingual cartilage; median ventral cartilage ; nasal aperture ; nch. notochord ; X'o. :i, foramen for optic nerve ; olfactory capsule ; pericardial cartilage; posterior dorsal cartilage; posterior lateral cartilage; sub-ocular arch ; styloid process ; styliforni cartilage ; t. teeth. of which and the brain-case are a couple of large overlapping cartilages : the tongue is supported by a long, lingual cartilage. On the mucous membrane covering the annular and lingual cartilages inside the oral funnel are a number of horny teeth. The fibro-cartilaginous olfactory sac is tin]jaircd, and opens on th
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
