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| Schenkkan, E.J.. |
| The aspects of the “connecting sac” are studied in Lagenorhynchus albirostris, Lagenorhynchus obliquidens, Lagenorhynchus acutus, Tursiops truncatus, Delphinus delphis, Phocoena phocoena, Sotalia guianensis, Stenella coeruleoalba and Stenella frontalis. Comparing the development of the connecting sac in the various species it is found that there are great variations. These variations are also found in the various individuals of the same species. For this reason the importance of this structure in soundproduction is open to doubt. The development of the connecting sac seems to be related to the development of the posterior part of the naso-frontal sac in such a way that, when a large and well developed posterior part of the naso-frontal sac is present, the... |
| Tipo: Article / Letter to the editor |
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| Ano: 1971 |
URL: http://www.repository.naturalis.nl/record/505059 |
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| Schenkkan, E.J.. |
| In the study of phonation in odontocete cetaceans and particularly that of echolocation by means of sonar, a great number of conflicting hypotheses have been advanced regarding the correlation of sound production with the many anatomical features that are to be found in the upper respiratory tract. The present paper follows a new approach via finding out if, and how, the various structures had evolued from the condition in the relatively primitive River Dolphins to the more highly specialized pelagic species. An introduction to the general anatomy of the upper respiratory tract is given, relating it to work previously published on this subject. A historical review of the various theories of sound production establishes the essence of the existing... |
| Tipo: Article / Letter to the editor |
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| Ano: 1973 |
URL: http://www.repository.naturalis.nl/record/504295 |
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| Schenkkan, E.J.. |
| The anatomy of the nasal passage of three specimens of the Boutu has been studied. The various diverticula appear to be aberrant from those described for other Platanistidae. The vestibular airsac system has developed into one enormous diverticulum. Except for a narrow region caudal to the blowhole, the total maxillary area caudal to the orbits is covered by this somewhat dome-shaped airsac system. The dorsal and rostral aspects of the vestibular system are strikingly symmetrical as are also the deeper parts of the nasal passage. The caudal parts of the nasofrontal diverticula are well developed, rostral parts are tubular and relatively small. Accessory air sacs are lacking and the premaxillary diverticula are broad, but their lumina rostral to the bony... |
| Tipo: Article / Letter to the editor |
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| Ano: 1977 |
URL: http://www.repository.naturalis.nl/record/504153 |
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| Schenkkan, E.J.; Purves, P.E.. |
| The nasal complex of Kogia has been compared with that of Physeter and shown to be homologous with that of less specialized ondotocetes. The nasal complex of the Physeterids is structurally related to that of the Platanistids and Ziphioids. The spermaceti organ unique to the Physeteridae forms a part of the functional morphology of the right naris and is not a bilaterally symmetrical structure like the melon of other odontocetes. Separation of the two nares in the Physeteridae is caused by the asymmetrical development of the spermaceti organ. In Kogia part of the musculature of the left naris actuates the opening of the right naris, a feature unique amongst the Mammalia. The right naris is not used in external respiration but forms an air reservoir... |
| Tipo: Article / Letter to the editor |
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| Ano: 1973 |
URL: http://www.repository.naturalis.nl/record/504039 |
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