. Bulletin of the Buffalo Society of Natural Sciences. Natural history; Science. BUFPALO SOCIETY OF NATURAL SCIENCES 41 Sclerotic ring (fig. ii).—A feature of great interest in this specimen is the preservation of a complete sclerotic ring, situated near the right orbit, and not far removed from its natural position. It is of great importance as affording for the first time a correct idea of the form of the eye in Dinichthys. Complete sclerotic rings of Arthrodira are extremely rare, owing to the fact that on dissolution of the animal the segments composing the ring became more or less disarra
. Bulletin of the Buffalo Society of Natural Sciences. Natural history; Science. BUFPALO SOCIETY OF NATURAL SCIENCES 41 Sclerotic ring (fig. ii).—A feature of great interest in this specimen is the preservation of a complete sclerotic ring, situated near the right orbit, and not far removed from its natural position. It is of great importance as affording for the first time a correct idea of the form of the eye in Dinichthys. Complete sclerotic rings of Arthrodira are extremely rare, owing to the fact that on dissolution of the animal the segments composing the ring became more or less disarranged and usually drifted apart. The most perfect example of an arthrodiran sclerotic ring hitherto known is the one belonging to the type specimen of Trachosteus, which was figured by Newberry {Paleoz. Fishes N. Amer., PI. xlii, fig. 2). It consists of four segments of very thin bone united by wavy sutures so as to form a Fig. II. Dinichthys magnificus, n. sp. Sclerotic Ring, Natural Size. Margin Restored Lowes In the present instance the sclerotic ring is not flattened down but preserves much of its original outward convexity, this convexity representing the configuration of the eyeball, which we thus learn was spherical as in other vertebrates. The ring is composed of four seg- ments; and the opening in the centre, corresponding to the eye proper, is not round but ovate, with the narrow ends drawn out to points. Its form is thus proved to have been much like that of sharks and many other fishes. The sclerotic ring measures 50 mm. in width, and 11 mm. in height. The eye opening is 20 mm. in long diameter (measured at the lateral angles), and 15 in greatest width. Mandible.—Only the left mandible is preserved, and this lacks the hinder third. Its form is well shown in the photograph reproduced in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustration
Size: 1726px × 1447px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, books, booksubjectnaturalhistory
