SKULL 879 



The Pterygoids are rod-shaped bones articulating in front 

 with the posterior end ^ of the Palatines, or also with the adjoining 

 part of the sphenoidal rostrum, and behind with a process of the 

 Quadrates. In many birds an additional articulation exists between 

 the Pterygoids and the Basisphenoid by means of the Basiptery- 

 GOiD Processes (p. 28). 



The Quadrates connect the lower jaw with the cranium, beside 

 serving for the posterior end of the Pterygoids, and lastly are con- 

 nected with the Maxilla and Prsemaxilla by two thin rod-shaped 

 bones — the Quadrato-jugal and the Jugal. 



The Mandibula forming the lower jaw is composed of a con- 

 siderable number of bones, most of which developing from membrane 

 invest the primitive cartilaginous portion, known as Meckel's Car- 

 tilage, and soon fuse with each other. The os articulare forms the 

 articulation with the Quadrate, and bears on its inner side the 

 processus mandibularis interims, which serves for the insertion of 

 part of the digastric muscle, or that which opens the mouth. The 

 OS angulare forms the posterior end of the mandible, and is frequently 

 produced into a j^^'ocessus mandibularis posterior; likewise ser'ving for 

 the insertion of the digastric muscle. Its shape and size are of 

 taxonomic value. The greater part of the Mandible is formed by 

 the Dentary, so called because in it the teeth when present are 

 lodged. In Hesperornis, Ichthyornis and apparently Gastornis the 

 two halves of the Mandible were movably connected at the distal 

 end : in recent birds they are fused together and ossify from the 

 point of meeting. The Supra-angular or Coronoid element fills the 

 space between the Articular and Dentary on the upper or anterior 

 side, and serves for the insertion of part of the temporal or masseter 



clidm, Columhm, Turnix, Ralli, Grxues (excl. Cariama and Rhinochetus, wliich 

 are incompletely Desmoguathous), Gallinai, Opisthocomus, Trogonidse, many 

 Striges, TrocMli, Caprimulgus, Nydibius, Pici, Megalmma and, as first men- 

 tioned, Fiirnariinse. 



Parker drew attention to the existence of three kinds of Desmognathism : — 



(1) Direct — where the maxillo-palatine processes fuse directly with each 

 other, either incompletely as in Cariama, or complete^ as in most Acdintres 

 and Aiiseres, with or without additional help from the internasal septum. 



(2) Indirect — where the fusion of these pi'ocesses is effected solely by that 

 septum, either incompletely as in Megalmma, or completely as in Aquila, 

 Vultur, several Striges and Alccdinidee. 



(3) Double — where those processes and the palatines meet in the middle line 

 and form a broad solid roof, as in Podargus and B%iccros. 



The following are Desmoguathous : — Drommus, Anscres, Steganoiwdes, Herodii, 

 Pelargi, Accipitres, Psittaci, Coccyges, Alccdinidse, 3Ieropidee, Tudidse, Upupidas, 

 Pucerotidee, Coliida}, Bucconidsc, Gallmlidee, Steatornis, Chordiles, Podargus 

 and Phaviphastidce ; lastly, the incompletely Desmoguathous Cracidaz, Cariama, 

 Rhinochetus and various Striges. 



^ At page 744 the "anterior end" was inadvertently stated. 



