1901.] SHUFELDT — OSTEOLOGY OF THE CUCKOOS. 35 



slender osseous bar, on either side, joining the pre- and postzyga- 

 pophyses, a character that gradually disappears in the next few suc- 

 ceeding vertebrae. Again, we see strong, median hypapophyses in 

 the last cervicals and some of the leading dorsals, and the neural 

 spines to the latter are much as we find them in Geococcyx only 

 being one or two more in number. Crotophaga seems in the main 

 to agree also in the nature and arrangement of its ribs ; they differ, 

 however, in the specimens before me by having a very rudimentary 

 pair on the twelfth cervical. There is also a peculiar pair of short, 

 stumpy ribs, detected considerably backward, articulating with the 

 first vertebra of the pelvis. 



The skeleton of the tail agrees practically with the same part of 

 the bird as we find it in Geococcyx, and this remark essentially 

 applies to the pelves of these species of Cuckoos — though in Croto- 

 phaga the ilia behind do not curl outward quite so much in pro- 

 portion, and the prepubic spine or process is relatively not so 

 large. 



As to their shoulder-girdles, Crotophaga sulcirostris and Geococcyx 

 agree pretty well, though in the former bird we find very notably 

 narrow scapulae, — long and pointed, while the hypocleidium to the 

 os furcula is relatively as large as we find it in most passerine birds, 

 being curved backward and upward, when the bones are in situ, 

 and occupies the lower part of the recess formed by the anterior 

 concaved border of the sternal keel. Os furcula itself is more 

 broadly rounded below than it is in Geococcyx. In other species of 

 Crotophaga these characters are not quite so strongly marked, ap- 

 proaching, perhaps, more nearly what we see in the Ground Cuckoo. 



One would now naturally suppose from the number of points of 

 agreement in the trunk-skeletons of these two species thus far 

 enumerated, that we would surely find their sterna modeled upon 

 the same plan. This, however, is by no means the case, for 

 although Crotophaga sulcirostris has essentially a cuculine sternum, 

 with a relatively deeper carina than has Geococcyx, 1 it differs radi- 

 cally in the xiphoidal portion of the bone, for it has but one 

 rather shallow notch upon either side ; whereas, as we have seen, 

 Geococcyx agrees with Coccyzus in possessing two. In Crotophaga 

 ani this shallow notching of the xiphoidal margin of the sternum 



1 This deeper sternal keel we might naturally expect to find, being a character 

 often seen when we come to compare birds that are by nature flyers, with those 

 that habitually spend the most of their time upon the ground. 



