SHOULDER-GIRDLE OF ICHTHYORXIS. 147 



Measurements of Coracoid. (Ichthyornis validus, No. 1446.) 



Longest diameter of humeral articulation, 8. mm 



Transverse diameter of humeral articulation, 4.2 



Least transverse diameter of shaft, below articulation, 4.5 



Vertical diameter of clavicular process, 5.5 



Transverse diameter of clavicular process, 3. 



Measurements of Coracoid. (Apatornis celer, ~No. 1734.) 



Left. Eight. 



Length of coracoid, 24. mm 



Length of humeral articulation, 5.5 



Transverse diameter of humeral articulation, 3.8 



Diameter of shaft below humeral articulation, 3. 



Vertical diameter of clavicular process, 5. 5. 



Transverse diameter of clavicular process, 2.5 



Diameter of sternal end, 14. 



The Clavicle. (Plate XXIX, figure 7.) 



The only portion of the clavicle yet known among the Odontotomies is a 

 fragment from the upper end of that bone, in Apatomis. This fragment is 

 considerably flattened, probably in part by pressure. It presents no face 

 for articulation with the coracoid, but tapers to a flattened point at the top, 

 where it is adapted for attachment to the acromial process of the scapula. 



The Sternum. (Plates XXIII, XXIX, and XXXIV.) 



The sternum in the type species of IcMhyomis is deeply keeled, affording 

 ample room for muscular attachment. The manubrium is broad, and some- 

 what unsymmetrical. The coracoid grooves are elongated, and overlap 

 widely across the median line, as in Ardea, and some birds of prey. As 

 usually occurs in living birds with this peculiarity, the inner end of the 

 left coracoid was above that of the right. These grooves become shallow 

 near the middle, where the ridge of bone behind nearly disappears, but, 

 toward the outer end, the ridge is again well developed, and acute. The 

 lateral margins and all the posterior part of the sternum are absent from 

 the type specimen of Ichthyomis dispar. 



The specimen of Iclithyomis victor (number 1461) in which the sternum 

 is preserved shows a strong and deep keel, robust and prominent in front. 



