The Nasal Organ in Amphibia
Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: THE NASAL CAPSULE OF THE GYMNOPHIONA EPICRIUM GLUTINOSUM Considerable diversity of opinion has existed in the past in regard to the systematic position of the Caecilians. Cope (1889) classed them as a family of the Urodeles, related to them through Amphiuma; while the cousins Sarasin (1890), following Cope, also regarded them as Urodeles, considering Amphiuma a neotenic Caecilian. Kingsley (1902) reviewed the evidence as to the position of the group, showing that many points supposed to indicate relationships, were based upon erroneous statements or misconceptions and that the Gymnophiona are to be regarded as a distinct group, without any close relations to any other existing Amphibia. To determine to what extent, if any, the nasal capsules of this group would shed light upon their relationships to the Ur
...odeles, two larvae of Epicrium glutinosum were studied, in which chondrification was well advanced and the nasal capsules completely formed. Peter (1898) has described the chondrocranium of a young Caecilian; and Winslow (1898) a stage in which the embryo is still spirally coiled within the egg, considerably younger than my earlier material. In contrast to all other Amphibia, the trabeculae of each side are double (Fig. 32), consisting of a dorsal and ventral bar in the position of trabecular crest and trabecula, the dorsal doubtless being the homologue of what Sewertzoff (1897) has called the alisphenoid cartilage of the Elasmobranchs. On either side of the eye, the dorsal and ventral trabeculae are united by a postorbital and preorbital band, the optic nerve passing through the large gap between them. Anterior to the preorbital band, the lower or true trabecula inclines toward the median line, and is united with its mate by a slightly convex planum basale (pb), whic... --This text refers to the Paperback edition.
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