OSTEOLOGY OF BIRDS 351 



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Coccystes possesses a sternum with the average cuculine char- 

 acters, but as compared with Cuculus canorus it exhibits one 

 noted difference, for in it the xiphoidal extremity is distinctly two- 

 notched upon either side, while in the same locality the common 

 cuckoo has but one, rather wide, shallow notch. Other cuckoos, 

 both Old and New World forms, vary in this respect, and the fact 

 that they do simply affords another example of the uncertainty of 

 this character, in so far as it possesses any positive taxonomic value. 

 As I have previously pointed out, an unnotched and unfenestrated 

 sternal body may exist in certain petrels, in all hummingbirds, 

 as far as known, in certain auks, and possibly in all swifts, while 

 there is no predicting, as yet, how many other existing birds may 

 be similarly circumstanced in this particular. 



Both Coccystes and Cuculus have the keel of the sternum rather 

 deep, proportionally deeper than in Crotophaga and others, with 

 a very prominent and produced carinal angle. This part of the 

 carina is carried forward in a somewhat " rakish " way, not to be 

 observed in Cuculus. In both the bone is pneumatic. 



Os furcula is of the usual cuculine U-shaped pattern with a 

 moderately large hypocleidium. Coccystes has this process, in the 

 articulated skeleton, in close contact with the superior edge of the 

 carinal angle of the sternum, to which it is fastened by strong 

 ligament in life. Such an arrangement is also seen to be the case 

 in Crotophaga, while in Cuculus the os furcula is well above the 

 carinal angle, and is no closer to it, in this species, than it is to 

 the manubrium above. This is an interesting point, the true sig- 

 nificance of which I am not prepared as yet to explain. A scapula 

 has a long and slender blade in Coccystes, carried out posteriorly to 

 a fine, sharp point or apex, this part of the bone being comparatively 

 shorter and more curved in Cuculus. 



In a coracoid of this example of the Great spotted cuckoo from 

 Syria, I note an unusual character, for not only is the conspicuous 

 outer process of its inferior expanded extremity of the shaft of the 

 bone present, as in other cuckoos whose osteology I have elsewhere 

 described, but there is also in evidence a corresponding mesial 

 process, produced directly upward from the inner lower angle of 

 the bone, that I find in no other species, though there is a rudi- 

 mentary indication of it in the common cuckoo of Europe. Coc- 

 cystes has a small os humeroscqpulare developed at its usual site 

 at the shoulder joint. 



