1914] Miller: Bird Remains from the Pleistocene of San Pedro 



33 



The commingling of marine forms with such vertebrates as the horse, 

 bison, camel, ground-sloth, passerine birds, and small chelonians sug- 

 gests a beach receiving appreciable contributions from the land. Such 

 a condition of affairs is perhaps explainable by Arnold's hypothesis 

 of alternate dune and water-laid beds represented in these deposits. 



DISCUSSION OF SPECIES 

 Gavia, sp. 



Specimen no. 21057 of the collection is a femur which at first 

 examination was referred to the genus Mchmophorus. The slender- 

 ness of the specimen fully equals that of a large grebe, and since the 

 condylar region was fractured to some extent there was thus obscured 

 to cursory examination one of the characters which distinguish the 

 grebes from the loons. Careful study of the specimen and comparison 

 with a series of the smaller loons, Gavia stellata and G. pacifica, easily 

 establish the relationships of the specimen to be with the genus Gavia. 



In a series of four individuals of the Recent loons, the variation in 

 length of the femur is almost inappreciable, while the thickness of the 

 shaft, as is commonly the case, shows a goodly range of variation. The 

 fossil femur under discussion is abruptly longer than the maximum of 

 the series at hand, yet it is actually more slender than the minimum 

 of the series. Further study of variability in the femur of the Recent 

 loons will be necessary before the identity of the fossil specimen may 

 with safety be announced, but it seems probable that the specimen 

 may represent a slender-limbed species distinct from the living forms 

 of Gavia. 



42. mm. 

 13. 



5.2 

 7.3 



Measurements 



Total length 



Transverse diameter at proximal end 



Least transverse diameter of shaft 



Sagittal diameter of shaft at middle point 



GAVIA near IMMER (Briinnicli) 

 The fragmentary tarsometatarsus of a large loon appears among 

 the material from San Pedro. The greater portion of the proximal 

 articular surface, the entire outer trochlea, and much of the middle 

 trochlea have been lost. In addition to these defects the specimen 

 was badly beach-worn before its final entombment, so that the trans- 



