933 



STRUTHIONID.E. 



STRUTHIONID.E. 



931 



is situated in the part corresponding to the above depression or sinus 

 in the jaw of Apteryx. Traces of the compound structure of the 

 lower jaw are very evident in that of the Apleryx, and the limits of 

 the angular, articular, and corouoid pieces may be in part defined. 

 There is a linear vacancy, bounded by the surangular and angular 

 pieces behind, and by the bifurcate commencement of the mandibular 

 or dentary piece in front ; the suraugular is compressed, and sends 

 upwards a very slightly elevated corouoid ridge. A second narrower 

 fissure occurs between the thick opercular or splenial element and the 

 upper fork of the mandibular piece. The opercular piece reaches to 

 the posterior part of the symphysis, as in the Ostrich, and the rest of 

 the lower jaw in frjut of this part is formed by the two anchylosed 

 mandibulars. In the extent of this anchylosed symphysis the KliM 

 makes the nearest approach to the Apteryx among the Sirulhionidce, 

 and the two impressions which diverge from the back part to the front 

 of the symphysis are present in both the Rhe.a and Emeu, as in the 

 Apteryx. The lower jaw of the Apteryx differs from that of the Ibis 

 in its greater posterior expanse, its more depressed form, the lower 

 coronoid plate, the narrower fissure between the angular and suran- 

 gular piece<, and the absence of the mesial furrow, extending in the 

 Ibis to the end of the symphysis." 



The number of the cervical vertebrae in the Ostrich is 18, in the 

 Cassowary 16 (true), in R/iea 16 (not 14, as Cuvier states), in the Emeu 

 19, in the Apteryx 15 only; and in the latter there are 9 dorsal and 

 22 remaining vertebrae in the lumbar, sacral, and caudal regions : the 

 spinal column of Apteryx is relatively stronger, especially in the 

 cervical region, than it is in the larger Struthumidie. 



In the Struthionida; we look in vain for the deep crista or keel 

 which so strongly marks the well-developed ornithic character, espe- 

 cially in the diurnal birds of prey, the larger sea-birds above alluded 

 to, and the Humming-Birds. Such a foundation would be worse than 

 useless where there is none of the machinery of flying to be worked, 

 and the utmost demand on the anterior extremities goes no farther 

 than their aid in balancing the body when the bird runs. We accord- 

 ingly find that in the larger Struthionida (Ostrich, Cassowary, &c.) 

 the breast-bone presents a plane and uniformly arched shield-like 

 surface, not unlike, in some of the family, the Cassowary and Emeu 

 for instance, to a Highlander's target on a reduced scale. Bui in the 

 Apteryx this low development is reduced to its lowest grade. In its 

 small size, and in the total absence of a keel, it resembles, Professor 

 Owen observes, that of the Struthious Birds generally, but differs in 

 the presence of two subcircular perforations on each side of the middle 

 line, in the wide anterior emarginations, and in the much greater 

 extent of the two posterior fissures. The anterior margin, he tells 

 us, presents no trace of a manubrial process, as in the Ostrich ; on 

 the contrary, the wide interspace between the articular cavities of the 

 coracoid is deeply concave ; in the extent of this interspace, he 

 remarks, the Rhea most resembles the Apteryf, but its contour is 

 almost straight ; whilst in the Cassowary the space is narrower, but 

 deeply notched. The articular surface for the coracoid is an open 

 groove, which in the fresh state is covered with articular cartilage ; 

 and, external to the groove, the anterior angles of the sternum are 

 produced into two strong triangular processes with the apex obtuse. 

 The thickened costal margin, when viewed anteriorly, presents an 

 undulating contour, from the presence of the four articular convexi- 

 ties, for the sternal ribs and the intermediate excavations. The 

 sternum of the Emeu, Professor Owen remarks, presents a similar 

 appearance. The breadth of each sternal perforation is, he adds, 

 nearly equal to that of the intervening osseous space, and in the 

 specimen described they were not quite symmetrical in position. The 

 posterior notches equal in extent one half the entire length of the 

 steruum, and the external boundaries of these notches curve towards 

 each other. These notches exhibit a slight want of symmetry in 

 form, position, and extent. 



There is no true furcula in the Struthionida, but the Ostrich and 

 Cassowary have on each side of the front of the chest an elongated 

 flat bone consisting of a rudiment of the furcula, with the clavicle 

 and scapula consolidated into one piece. The two branches of this 

 rudimentary furcula are very short, and never united in the African 

 Ostrich, but anchylosed with the bones above mentioned. In the 

 Cassowary there are merely two little processes from the side of the 

 clavicle ; these are the rudiments of the branches of the fork. In 

 the Emeu two very small thin bones are attached to the anterior 

 edge of the dorsal end of the clavicles by a ligament, and are directed 

 upwards towards the neck ; there they are fastened to each other by 

 a ligament, but have no connection with the sternum. In the Apteryx 

 the scapula and coracoid are anchylosed ; and a small perforation ante- 

 rior to the articular surface of the humerus indicates the separation 

 between the coracoid and rudimental clavicle, of which, Professor 

 Owen states, there is not otherwise the least trace. The coracoid, he 

 adds, if the strongest bone ; and its inferior expanded extremity pre- 

 sents an articular convexity, adapted to the sternal groove before 

 described. The third rib is reached by the scapula, which is a simple 

 narrow plate of bone, an inch in length, slightly curved, and expanded 

 at both ends, chiefly at the humeral articulation. 



The true wing bones are best developed among the Struthious 

 Birds in Rhea : the next best development is in the Ostrich ; in the 

 Cassowary, Emeu, and Apteryx, the lowest development of these bones 



is exhibited. In the latter the humerus is a slender cylindrical styli- 

 form bone, 1 inch 5 lines in length, and slightly bent. At the two 

 extremities it is slightly expanded, but most at the proximal end, 

 which supports a transverse oval articular convexity, covered with 

 smooth cartilage, and joined by a synovia! and capsular membrane to 

 the scapulo-coracoid articulation. Beyond each end of the humeral 

 articular surface is a small projecting tuberosity. The distal end of 

 the humerus is articulated by a true but shallow ginglymoid joint 

 with the rudimental bones of the antibrachium, and both the external 

 and internal coudyles are slightly developed. The slender radius and 

 ulna, each 9 lines in length, are almost straight and cylindrical. 

 Above the articular surface of the ulna a feebly-developed olecranon 

 is projected. A minute carpal bone, two metacarpals, and a single 

 phalanx, which supports the lonij curved obtuse alar claw, complete 

 this rudimental hand, which is 7 line-i in length, including the claw, 

 and that measures 3| lines. To the ulna au<l metacarpus a few short 

 and strong quill-feathers are attached by ligameat. 



Skeleton of Ostrich. ( Ponder and D' Alton.) 



skeleton of ^/j/rryz. (Owen.) 



