C R. Eastman — Another Egg of Siruthiolithus. 437 



weathered side is that shown in the accompanying figure, repro- 

 duced from a photograph, and on this several areas are to be 

 observed where the original shell has remained unaltered. Some 

 discoloration has been brought about through the agency of iron 

 oxide, and grains of ferruginous sand still adhere to the shell in 

 places, or are even partially embedded in the crust. This side of 

 the shell is of a brownish yellow colour, somewhat darker than the 

 opposite or more weathered side. Numerous fine pittings are to 

 be seen over the greater part of the periphery, especially in the 

 equatorial region, some of which may be due to destructive agencies, 

 but the majority of them are clearly to be regarded as the round 

 terminal pores of air-canals. To determine their precise relation- 

 ships it would be necessary to sacrifice a portion of one of the best 

 preserved areas for the purpose of making a thin section, but as 

 no such area is contiguous to the aperture at one end cut by 

 Mr. Sprague, and as sections from the polar regions afford but little 

 information, no further mutilation has been attempted. Indeed, it 

 is doubtful in any case whether a section would show more than 

 has already been ascertained from Nathusius's study of the type- 

 specimen, which merely proved that the air-canals terminated in 

 a similar fashion as in Struthio camelus. 



As to the age of the deposit from which the specimen was 

 exhumed, it is reasonably certain from the accounts furnished by 

 Mr. Roberts and Mr. Sprague, the former of whom related his 

 observations in full to the writer, that no earlier date can be assigned 

 to it than the Pleistocene. The gravel bank yielding the remains 

 is situated in a loess basin which is drained by the Sang Kan. 

 Such basins are not uncommon along the upper course of this river, 

 and are mentioned by Von Richthofen and Pumpelly in their works on 

 the Geology of China. According to Von Richthofen, the superficial 

 deposits of these basins were laid down over the bottom of isolated 

 salt lakes having no outlet, and were afterwards buried by alluvial 

 detritus. Traces of former shore-lines exist along the mountain 

 sides, and one is confronted on every hand with the evidence of 

 recent dessication. The moderate depth to which ravines have cut 

 through the former lake beds, and the straight narrow gorge of the 

 Sang Kan, through which their waters were drained off, corroborate 

 the belief that this event took place at no very remote period — 

 in all probability since the Pleistocene. The occurrence of fossil 

 ostrich remains in such widely separated regions as Northern China 

 and Russia during the late Tertiary has a signal bearing upon the 

 distribution of Struthious birds. The only existing representative 

 of the Struthionidfe {S. camelus) is confined to Africa and Arabia, 

 but the Pliocene of the Siwalik Hills in India has yielded a closely 

 related species (S. Asiaticus), and other remains, described as 

 S. Karaiheodoris, have been found in the Lower Pliocene of Samos. 

 On the theory of the multiple origin of the Ratitae, we are obliged 

 to disclaim any genetic relationship between Strutliio and other 

 Oriental forms commonly classed as Struthious birds, such as the 

 emeu, cassowary, and extinct wingless birds of New Zealand. But 



