DEVELOPMENT OF ANI 310 



'J'AKSO-MKTA'I'AKSUS 



Thv inatiirc tarso-iiictatarsus is curiouslv ridiied and 

 grooved, the f'ourtli metatarsal })eiii(4- Hattened so as to foiin 

 a ridn-e a})()ve the otlier hones. The seeond metatarsal is 

 miieh flattened and seems almost to he separated from the 

 others, heino- eonneeted. j)artienlarly on the proximal half, 

 oidy hy a thin, transparent sheet of ])()ne. In the emhryo, 

 however, this is not true. As late as the period when the 

 hird leaves the nest all the metatarsals, thouo-h totally fused, 

 are still rounded. There is just a slioht hroadening of the 

 hones and a eommeneement of the "rooves, with no Hattenino- 

 oi the fourth metatarsal. 



BILL 



The exaggerated development of the eulmen takes 

 place only after the Hedgling has left the nest. In the newly 

 hatched chick, the hill is short and swollen, but in all respects 

 typically cuckoo-like. The eulmen is angled histead of 

 curved, but as the bird grows older the angles decrease and 

 curves take their place. The commissure is greatly curved 

 until the cuhiien begins to ridge up and then straightens as 

 the ridge forms. The lower mandible is much shorter than 

 the upper and the gonys is narrow and very angular. The 

 projecting hook of the upper mandible gives the young bird 

 a rather hawk-like appearance. The gonys lengthens very 

 slowly, so that at least three months pass after fl^'ing before 

 the bird attains its full eulmen ridge and its wide flat gonj^s, 

 which pushes forward so as almost to fill the notch caused 

 by the curved tip of the upper mandible. 



