58 SYSTEMATIC PALEONTOLOGY 



Cetacea a very primitive position, making them the ancestral form 

 of the mammals.^ This idea has gained little credence. The settle- 

 ment of the question must await further discoveries. Certain it is 

 that the earliest forms that we know have already reached a very high 

 degree of specialization, so high as to command a belief in an earlier 

 origin than the fossils so far found would indicate. 



Class AVES. 



ot-der STEGANOPODES 



Family SULIDAE (Gannets). 



Genus SULA Briss 

 SULA LOXOSTYLA CopC. 



Plate XXVI, Fig. 2. 



Sula loxostyla Cope, 1871, Trans. Amer. Philos. Soc, vol. xiv, pp. 236, 337, fig. 53. 



Description. — " This species is established on a single coracoid bone 

 which I found at the foot of the Miocene cliffs in Calvert Co., Mary- 

 land. The furcular articular surface is broken off, as well as the 

 exterior half of the posterior or sternal articular extremity. The 

 extremity of the scapular surface is also injured. Sufficient of the 

 bone remains to furnish many characteristic peculiarities, and to indi- 

 cate its affinity to the totipalmate family of the Gannets or Sulidje. 



" The bone is stout, and indicates a bird of strong flight. The shaft 

 proper is rather short, and subcylindric, with a trihedral tendency. 

 This form, with the expanded distal extremity, indicates its wide dis- 

 tinction from the coracoid of the Gallinacese. Its subcylindric shaft 

 marks considerable difference from the Lamellirostres and many other 

 aquatic types. Its lack of inner subclavicular ala and foramen, dis- 

 tinguishes the type from Eaptores, the majority of the Longipennes and 

 many Grallaj. The presence of a marginal groove or rabbett distin- 

 guishes it not only from most Psittaci and Insessors, but from many 

 Xatatores also. After a study of the large collection of bird skeletons in 



' Ueber die Cetoide Natur der Prommammalia, Anatomischer Anzeiti^er, 1, p. 338, 

 1886. 



