1901.] SHUFELDT — OSTEOLOGY OF THE CUCKOOS. 25 



at the outer termination of a coracoidal groove, and running back- 

 ward to a point about opposite the middle of the keel. 



The coracoidal grooves do not meet at the manubrial base in the 

 median line, and each one is characterized as being a deep trans- 

 verse notch, with upper and lower lips of projecting bone and ex- 

 tending laterally only so far as the inner or anterior limit of the 

 base of the corresponding costal process. My former memoir in 

 the Journal of Anatomy gives figures of the sternum of Geococcyx. 

 With respect to the pectoral arch, I find a coracoid to be, compara- 

 tively speaking, an unusually long bone ; its sternal or lower border 

 extends beyond the facet proper, in order to fit into the coracoidal 

 groove of the sternum. This end of the coracoid is not as much 

 expanded as we find it in some birds, but, on the other hand, like 

 many of the Class, its outer angle is produced and bent upward as 

 a projecting process. 



The shaft is long and cylindrical, being marked down its posterior 

 and lateral aspects by muscular lines. 



At the superior, or really anterior extremity of this bone we 

 find several noteworthy and interesting characters. Its scapular 

 process is very long, and compressed from side to side. This 

 apophysis reaches forward, and by its slightly dilated extremity 

 articulates with a vertically concave notch in the lower part of the 

 head of the corresponding clavicle. 



Another meeting between these two bones takes place above, and 

 this is effected by the summit of the coracoid curving inward 

 toward the median plane, to articulate with a considerable facet 

 found at the highest point of the clavicular head. 



These two articulations between the furculum and the coracoid 

 completely close the tendinal canal, even without the assistance of 

 the scapular behind, though this latter bone materially aids in in- 

 creasing the actual length of this tendinal passage, by closing up 

 the posterior gap. 



The os furcula has a form about intermediate between the usual 

 U- and V-shapes of the bone. Regarding it from a lateral aspect, 

 the actual form of one of its transversely compressed heads can be 

 better appreciated, as well as its method of articulation with the 

 other bones of the girdle. This part of the skeleton of Geococcyx 

 has all been figured in my former memoir on its osteology in the 

 four?ial af Anatomy. 



Below it is flattened in the antero-posterior direction, and termin- 



