. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. TEETH or FISHES. 309 »&- /.i .?ff-* fig'. 250, c, opposed to two dentigerous pharyngeal jaws, d, d, below. Ill the Lcpidosircu a single maxilhuy dental plale, hg. 251, II, is o]i[)osed to a single mandibular one, h, and there are two small dentieles on the nasal bone, c. In the extinet Sharks with crushing teeth, called Ceratudus and Ctenodus, the jaws were armed with four teeth, two above and 217 two below.' In the Chim;\;r;c two £s:y<;rS^\ mandibular teeth are opposeil to four . ^ maxillary teetli.^ From this
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. TEETH or FISHES. 309 »&- /.i .?ff-* fig'. 250, c, opposed to two dentigerous pharyngeal jaws, d, d, below. Ill the Lcpidosircu a single maxilhuy dental plale, hg. 251, II, is o]i[)osed to a single mandibular one, h, and there are two small dentieles on the nasal bone, c. In the extinet Sharks with crushing teeth, called Ceratudus and Ctenodus, the jaws were armed with four teeth, two above and 217 two below.' In the Chim;\;r;c two £s:y<;rS^\ mandibular teeth are opposeil to four . ^ maxillary teetli.^ From this low point the number in ditferent Fishes is })ro- gressively multiplied until, in the Pike, the Siluroids, fig. 252, and many other fishes, the mouth becomes crowded with innmnerable teeth. With respect to form, I may pre- mise that as organised beings with- draw tliemselves UKH'e and more, in their ascent in the scale of life, from the influence of common physical agents, so their parts progressively deviate from geometrical figures : it is only, therefore, in the lowest ver- tebrated class that we find teeth in the f(.)rm of perfect cubes, and of j)rlsms or jilates with three sides (^Blijlcfes), four sides ( Scancs), five, or six sides (^MijUohutcs, fig. 249). The cone is the most connnon form in Fishes: such teeth may be slender, sharj)- ojg pointed, and so minute, numerous, and closely aggregated, as to resemble the plush or pile of A'eh'ct; these are called ' villifbrm teeth' (di'/ifes villiformes, dents en velours^); all the teeth of the Perch arc of this kind : when the teeth are equally fine and numerous, but longer, they are called ' ciliiform' {denies ciliifunnes) : when the teeth are similar ty Ciivicr in xxiii. passim. VOI-. I. B H s^J*.-- â J. â¢' i» J » octiou i>f 1, Of Onjdcrojiii!' mayn. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance o
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1860
