248 THE ANATOMY OF VERTEBRATED ANIMALS. 



presents no fontanelle. There is no distinct epicoracoid. The 

 two bones take nearly equal shares in the formation of the 

 glenoidal cavitj-, and usually remain unanchylosed and distinct 

 in this region. 



In the Matitce the long axis of that part of the scapula 

 ■which lies near the glenoid cavity is parallel or coincident with 

 that of the coracoid, and the two bones become completely 

 anchylosed. But, in all the Garinatm, the long axis of the 

 scapula forms an acute, or only slightly obtuse angle ( Ocydro- 

 mus, Didus) with that of the coracoid. A small bone, the 

 scapula accessoria, is developed on the outer side of the shoul- 

 der-joint in most Coracomorphce and Celeomor^jJicn. 



In the CarinatGB, the glenoidal end of the scapula is divided 

 into two portions ; a glenoidal process, which expands to form 

 the upper part of the glenoidal cavity, and to unite with the 

 coracoid, and an acromial process, which gives attachment to 

 the outer end of the clavicle. The glenoidal end of the cora- 

 coid is in like manner divided into two portions ; a glenoidal 

 process, which unites with the scapula, and a clavicular process, 

 which articulates with the outer surface of the clavicle, near 

 its outer end. 



The clavicular process of the coracoid probably represents 

 the procoracoid of Lacertilia. In the Rcititce there is no dis- 

 tinct clavicular process, but the anterior part of the coracoid, 

 near the glenoid cavity, may be produced and separated by a 

 notch, or fontanelle, from the rest, as a lacertilian procoracoid. 

 There is no trace of clavicles in the Apteryx and in some Par- 

 rots. In the Emeu, and in sundry Garinatm (some Parrots 

 and Owls), the clavicles remain distinct from one another, or 

 connected only by fibrous tissue ; but, in the majority of birds, 

 they are very early anchylosed together, and with the repre- 

 sentative of the interclavicle, in the middle line, into a single 

 bone, the furculwn, the strength of which bears a pretty close 

 relation to the exertion required of the wings in ilight, or in 

 natation. In the passerine birds the scapular end of the clav- 

 icle is usually expanded, and ossifies separately, as an epiclei- 

 diuin. A median process [hypocleidiwin) is frequently devel- 

 oped from the interclavicular part of the furculum, and this 

 may be united with the carina of the sternum by strong fibrous 

 tissue, or even by continuous ossification. In Opisthocomus, 

 the furculum is anchylosed with the manubrial part of the ster- 

 num, on the one hand, and with the coracoids on the other. 

 Anchylosis of the furculum with the coracoids has also been 

 observed in Didus. 



