150 



MEMOIES OF THE CARNEGIE MUSEUM 



The pneumatic foramen in the femur of S. cyanops is usually very large, and 

 comparatively small in my specimen of S. piscator. This also applies to S. brewsteri, 

 but in Sula gossi it is notably very large again. The general characters of the femur 

 are much alike in all typical Gannets. 



The ti bio-tarsus and fibula in Sula cyanops agree with those bones in S. bassana, 

 as they practically do in other species. There is a difference seen in the degree of 

 distinctness of the distal end of the fibula. The entire bone can easily be made out 

 in all my specimens of S. gossi, and only, or less than, the distal fourth of it fuses 

 with the tibio-tarsus in that species. The tibio-tarsal condyles are far apart in S. 

 piscator and S. gossi, and in most birds of this family this character is more evident 

 than it is in S. bassana. In this last-named species the tibio-tarsus and tarso-meta- 

 tarsus are all non-pneumatic ; I fail to find any pneumatic openings in the tibio- 

 tarsus of ;S'. cyanops, but the tarso-metatarsus of that species enjoys that condition 

 to a very high degree, as numerous and large air-holes are found about the head 

 of the bone. Another remarkable fact is that the tarso-metatarsus in Sula cyanops 

 is rather larger than that bone in Sula bassana. It is very small in S. piscator, and 

 in all considerable variation may exist in the hypotarsus, for the places where the 

 tendons pass through may be either grooves or perforations. Whatever they are, 

 however, they never exceed two in number. Below I give a table showing the com- 

 parative lengths of these bones in the species under consideration. 



Measurements in Centimeters and Fractions. 



Species. 



Femur. 



Tibia. 



Tarso-metatarsus. 



Middle Anterior 

 Toe. 



Sula bassana. 

 Sula cyanops. 

 Sula piscator. 

 Sula gossi. 

 Sula brewsteri. 



7.4 

 6.4 

 4.9 

 5.4 

 5.9 



10.9 

 9.9 

 6.9 

 7.9 

 9.1 



6.1 

 6.5 

 3.8 

 4.9 

 5.7 



7.9 

 8.3 



From this study it is hardly necessary to add that the skeleton of the pectoral 

 and pelvic limbs of the Sulidse is entirely different from the corresponding parts and 

 bones in the Phdethonidce. 



Anhingid^. 



Osteology of Anliinga anhinga. 

 As will be seen by my list of material given above, I have, at the present writ- 

 ing, but a single skeleton of this family of birds, before me for examination. It is 

 complete, however, and there are at hand the accounts of the osteology of Plotus 

 by other authors. Doctor R. Bowdler Sharpe in his recent Hand List of Birds 



