OSSEOUS SYSTEM OF AVES. 57 



e.g. Cracticus, Aiithochcera, Lanius, amongst Cantores, but chiefly 

 in the aquatic, wading, and terrestrial orders ( Tetrao, Dinor- 

 nis, Didus, Notornis,^ Porphyrio, Tantalus, Rhyncops, JJria^. 

 The Coots show a second elliptical vacuity at the base of the 

 coronoid rise of the surangular.^ In Rhyncops, the long com- 

 pressed symphysial part of the mandible descends below the 

 level of the angular, the lower border of the mandible having a 

 deep notch there. The symphysial part partakes in a minor 

 degree of all the various modifications of the lower mandible. 

 The angular is chiefly extended transversely, and to the inner 

 side of the ramal axis, to form the surfaces adapted to the tympa- 

 nic condyles, a deep and smooth depression usually dividing 

 them : the inner joint, in Parrots, is a longitudinal groove ; the 

 outer one is a longitudinal convexity. An angular process 

 extends from the inner or medial side of the articular expansion ; 

 there is also, in some birds, a similar process from its back part, 

 and this, in the Grouse tribe, especially the male Urogallus, is 

 much elongated and bent up. The temporal muscles are inserted 

 into an elongate rough tract, or slight elevation of the upper 

 border of the surangular : it is rarely raised into a ' coronoid ' 

 process ; but this is conspicuous in the conirostral Cantores, and 

 especially in the Grosbeak and Crossbill. The latter bird shows 

 a want of symmetry in the mandibular rami ; and there is a large 

 sesamoid, wedged into the back and inner part of the joint of the 

 lower jaw.^ 



Through the arrested developement of tlie hyoid arch (cerato- 

 and stylo-hyals), the tongue of Birds is not suspended by attached 

 inverted piers, but is slung to the cranium, when its branches are 

 suflficiently long, by ^ thyro-hyals,' usually including the hypo-, figs. 

 26, 31, 46, and cerato-, ib. 47, branchial elements; they are long 

 and slender. The basihyal, figs. 26, 31, 33, 4i, hh, is subcylindrical 

 and expanded at the ends ; the front end usually presenting a 

 trochlear articular surface, convex transversely, concave vertically, 

 for the glossohyal, or for the ceratohyal, or for both elements. 

 The ceratohyal, ib. 4o, ch, is always short, usually extending for- 

 ward from its attachment as well as backward, and the forAvard 

 production often unites with its fellow, so as to form the basal 

 part of the direct support of the tongue. In this case the glosso- 

 hyal, ib. 42, articulates with the ceratohyals ; rarely also ^^Ai\\ 

 the basi-hyal, hh, as in tlie Crane, fig. 33, c. The basihyal is of 



* XV1-, vol. iii. pi. 53, fig. 1. ^ Ib. figs. 1 and 7, w. 



3 VII-. p. 277. 



