Articoli correlati a Devonian fishes of Iowa Volume 18
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 Excerpt: ...Cranial shield much arched from side to side, completely enclosing the orbits, and extending over the nuchal region posteriorly. External surface covered with fine stellate tubercles which conceal the underlying sutures between dermal plates. Median series of the latter but two in number, narrow and elongate; external occipitals large; centrals divided, the two pairs on either side not meeting their fellows in the median line. Pineal foramen inconspicuous, situated slightly in advance of a line joining the anterior borders of the orbits. Sensory canals forming large tubular excavations in the bone, opening at the external surface by a continuous narrow slit or by a double series of pores. Parachordal cartilage and notochordal sheath calcified. Nature of dentition unknown, although there is apparently an articular cavity for the lower jaw. No indications of abdominal armoring. The typical genus of this family is Macropetalichthys, known by a single American, and two or three European species. In addition, an undescribed species is reported by Jaekel from the Middle Devonian of the Eifel District, in Rhenish Prussia, the type of which is in the Senckenburg Museum at Frankfort, and at the same time the form described by Kayser in 1880 as M. pruemensis is made by Jaekel the type of a distinct genus.f All these forms evidently stand in close relation to Homosteus as regards number and general arrangement of cranial roofing plates, position of the orbits, and in having the headshield prolonged posteriorly over the nuchal region. It is perhaps of some significance to note that the median series of cranial plates are reduced to the same number as in Neoceratodus, and are fewer than in Dipterus. Science, 1905, 21, p. 297.--See also Yearbook Carnegie Inst. Wash. 1904...
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- EditoreRareBooksClub.com
- Data di pubblicazione2012
- ISBN 10 1130895106
- ISBN 13 9781130895100
- RilegaturaCopertina flessibile
- Numero di pagine112
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