Ron Bout, Herman Berkhoudt, Angélique van der Leeuw, Karin Kurk and Peter Snelderwaard

alternativehypothesis, that feeding on water plants may have led to the evolution of ridge-like structures in the bills, a sliding mandibular joint and the use of a water  ow through the oropharynx (tongue pro- and retractions) for food transport in early anseriforms (cf. geese). A selection pressure on Ž lter

R. Uribe and F.A. Sibbing

-viscosity sialomucines occur in the anterior part of the oro-pharynx. They will serve maintain- ing a laminar flow during suction and lubrication of particle handling in the pharynx. Epithelial microridges may aid in holding the mucus. High-viscosity sulfomucines on- ly appear in the posterior part of the pharynx and

Melissa Barkat-Defradas

Indeed, it is well known that, in addition to oral consonants, speakers of Arabic distinguish between a number of sounds which exhibit an anterior primary articulation coupled with a secondary articulation resulting from the pulling of the back of the tongue toward the back wall of the oropharynx

G.A. Zweers

a variety of physical mechanisms of taking water in the oropharynx and then swallowing it. In tip up drinking the water is taken in the oropharynx by a few motion cycles of beak and tongue while the beak tips are immersed. The gathered water mass is stored in the oropharynx while tipping up. That

Brechje Lendering, Jan Heidweiller and Gart A. Zweers

pattern development of the cervical column may be further elucidated by in- cluding the functional demand that the water (ingested during immer- sion) must stay in the oropharynx during the upstroke (see HEIDWEILLER & ZEERS, 1992). To meet this demand in each on- togenetic stage, the trajectory of the

A.H.J. Van Der Leeuw

transported from the oropharynx to the esophagus against adhesive forces. During this phase, the beak tips are positioned up- wards in such a way that the force of gravity contributes to the water transport. I assume here that these demands on the cranio-cervical motion pattern are the same in all waterfowl

G.A. Zweers and H. Berkhoudt

pharynx shows this feature, since the trachea debouches here via the larynx into the oropharynx. The floor should therefore have a multi-purpose construction, meeting the different functional demands posed upon it. The anatomical integra- tion of structural elements in such a construction can occur in 3