. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. Hyo-brancliijil Xranu', skull, Tiidiirile. oxxxix. liypotympanic, fig. 43, 29. The parietals, ib., 44 and 68, 7, and afterwards the frontals, ib. ib., u, progressively cover the 'fon- tanelle ' above, as the basioccii^ito-sphenoid covers the hypophj^sial vacuity below. An antorbltal plate, fig. 72, b, extends from the frontal to the maxillary. The premaxillaries, at first beak-shaped, figs. 42, 22, and 69a, ?«, expand transversely as the mouth widens to form its fore-part, fig. 71, n: external to the premaxillary pedicle
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. Hyo-brancliijil Xranu', skull, Tiidiirile. oxxxix. liypotympanic, fig. 43, 29. The parietals, ib., 44 and 68, 7, and afterwards the frontals, ib. ib., u, progressively cover the 'fon- tanelle ' above, as the basioccii^ito-sphenoid covers the hypophj^sial vacuity below. An antorbltal plate, fig. 72, b, extends from the frontal to the maxillary. The premaxillaries, at first beak-shaped, figs. 42, 22, and 69a, ?«, expand transversely as the mouth widens to form its fore-part, fig. 71, n: external to the premaxillary pedicles liegins the ossification of the turbinals. The 'pterygoid plate,' fig. 43, 24, extends to the inner side of the hypotympanic, 29, and forward to the ' palatine ' bone, and the bifid dentigerous 'vomerine' plate, fig. 73, I, I. From the membrane covering ' Meckel's cartilage,' figs. 69a and 70, d, are exclusively developed the mandibular elements, the ' angular,' fig. 43, so, and ' dentary,' ib. 32, being the chief; there is also a ' splenial,' which in some perennibranchiate Batrachia supports teeth. As the mandible, fig. 71, (/, lengthens, the tympanic, il). e, shortens and becomes more vertical, and the hyoid arch, ib. a, shifts its attaclmient to the i)etro3al, close Ijchind, but distinct from, the tympanic. In the Lepidosiren the ali- and orbito-sphcnoids and the tympanic remain cartilaginous; premaxillaries are represented by their ascending or facial parts coalesced into a single l)late, sujiporting the two pre- Iiensile teeth. The postorbito- supcrtemporals, fig. 41, 12, are ' dermal' or scleral bones, over- la2:)ping the fronto-parietals. They are not present in modern Batrachia. In the Axolotl [Axulotes marmoratus), the basioccipital is repre- sented by the posterior part of the common broad and flat basi- cranial bone. The exoccipitals are separated below by this process, and above by a cartilaginous representative of the superoccipital. Each exoccipital developes
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1860
