THE FOSSIL AVIFAUNA OF THE 
309 
LaRUS PHILADELPHIA. 
A nearly perfect humerus and the distal half of another in Profe.ssor Cope s 
collection agree in all particulars with the humerus of a specimen of this Gull in my 
own private collection. The species apparently was not abundant during tertiary 
time in the Silver Lake region, or I must believe more examples woidd have been 
found. 
This fossil was collected in the same locality as the last described species, by 
Mr. Charles H. Sternberg, 
Xema sabinii. 
There is a fine specimen of the left humerus of a Gull of this species in the 
collection of Professor Condon, which agrees in every detail with the cori-esimnding 
bone of a specimen of Xema sabinuYo. the collection of the U. S. National Museum 
(No. 93,429). It too, must have been a rather rare form in the tertiary avilaumi 
of Silver Lake. 
This fossil specimen was collected in the Equus Beds of the Silver Lake region 
of Oregon by Professor Thomas Condon of the University of Oregon at Eugene City. 
Sterna elegans? 
Professor Cope’s collection contains two humeri and three carpo-metacarpi of a 
large Tern that for the lack of proper material I have not been enabled to fully 
determine. They may have belonged to this species,— a Pacific Coast Tern of the 
present day. 
Fossils collected in the same locality as the last by Mr. Charles H. Sternlierg. 
Sterna eosteei? 
This is a smaller species than the last, and in Professor Cope’s collection J <>'*‘1 
two perfect coracoids, two carpo-metacarpi, and a humerus (imperfect) of a Tern, 
which, in the absence of more complete material, 1 provisionally ivfer to this 
specie! They belonged to a larger bird than either Sterna antillarum or Hydro- 
chelidon nigra surinamensis (Gmel.), and I have carefully comjiared them 
skeletons of both those fomis. In the avifauna of the present day, Fosters Tern 
has a general distribution over all North America. 
Mr. Sternberg also collected these fossils in the Silver Lake region of Oivgon. 
Hydeochelidon nigea surinamensis. 
A single humerus (not quite perfect) of this species is in Professor Cojic’s col- 
lection I have compared it with the corresponding bone of a Black Tern kdonging 
to the collections of the U. S. Museum (No. 17,688), and find it to agm- sii closidy 
that there can be no doubt as to its identity. No other bones of this siiecies were 
Collected at Fossil Lake, Oregon, by C. II. Sternberg for Professor Cojie. 
I have reason to believe that other Gulls and Terns existed in the avifauna of 
the region under consideration during the later tertiary time, but the material in 
the collection is too fragmentary, beyond what has been given almve, to make them 
