160 



MEMOIRS OF THE CARNEGIE MUSEUM 



Fig. 5. Ventral aspect of the sterniira of Anhinga anhinga. 



Fig. 6. Left lateral view of the same bone shown in Fig. 5. 



Fig. 7. Anterior aspect of the osfurciiln of Anhinga anhinga. 



Fig. 8. Mesial side of the scapular end of the same bone shown 

 in Fig. 7. All the cuts are natural size from the specimen (No. 

 18259, Colls. U. S. Nat. Mus.). Outline drawings by the author. 



The Sternum and Shoulder 

 Girdle. — Many of the characters 

 of the sternum of a Darter es- 

 sentially agree with the corre- 

 sponding ones as they occur in 

 the sternum of such Cormorants 

 as represent the genus Phalacro- 

 corax. Its carina dies out on the 

 under surface of the body before 

 arriving at the mid-xiphoidal 

 process behind ; and is deep only 

 in front, where it protrudes for- 

 wards, with a sharp anterior bor- 

 der, and bears a large facet, oc- 

 cupying the carinal angle, for 

 articulation with the os furcula. 

 Only the merest rudiment of a 

 manubrium is to be seen at the 

 usual site ; possibly the process 

 is entirely absent in some speci- 

 mens. A wide concave notch 

 separates the coracoidal grooves 

 mesiad, and the large, elongated 

 coracoidal facets above them. 

 Large, acutely triangular costal 

 processes are developed, each one 

 projecting outwards at an angle 

 of about 45°, and very slight 

 forwards. The costal borders 

 are short and much contracted ; 

 either one supports four trans- 

 verse hsemapophysial facets. 

 Posterior to the costal borders the 

 sternum widens, and its lateral 

 margins are sharp. Its hinder 

 border is also sharp. Two large, 

 broadly concave notches exist 



