of Vertebra from Cape Colony. 341 



locality, Tamboer Fontein, where it was found, and the 

 friendly help of the gentleman, Mr. J. S. Marais, VA'lio aided 

 me in collecting larger fossils upon his farm. 



Doubt has of late been current concerning the significance 

 of pneumatic foramina in fossil bones, and is put forward 

 verbally and in print by Professor H. F. Osborn. In an 

 article in the ' Century Magazine ' for September 1904, 

 similar in scope to the lecture given at Cambridge in August 

 to the British Association, he enunciates the same views. 

 Writing of Omitholestes, Professor Osborn remarks : — " Ex- 

 ternally its bones are simple and solid-looking, but, as a 

 matter of fact, they are mere shells, the walls being hardly 

 thicker than paper, the entire interior of the bone having 

 been removed by the action of the same marvellous law of 

 adaptation which sculptured the vertebraj of its huge con- 

 temporaries. There is no evidence, however, that these 

 hollow bones were filled with air from the lungs, as is the 

 case of the bones of birds.''' 



Omitholestes is compared with Coelurus, Hallopus, Orni- 

 thoinimuSj and Aristosuchus. It is known from the skull, 

 forty-five vertebras, pelvis, and representative parts of both 

 fore and hind limbs of one individual (Bull. Am. Mus. Nat. 

 Hist. vol. xix. p. 459). But from the context quoted I 

 gather that the author's conclusions should be applied not 

 only to Omitholestes, but to the pneumatic vertebras of the 

 largest Dinosaurs, possibly to all fossil pneumatic bones 

 which are not referable to birds. 



The current belief that a pneumatic vertebral column is 

 evidence of the prolongation into the bones of air-cells from 

 the lungs is an inductive conclusion, based upon the evidence 

 from the parallel condition in the bones of birds. This 

 evidence is affirmed by Prof. Osborn, in the passage quoted, 

 not to exist, and in place of it he ofters what is termed the 

 " Law of Adaptation " as having sculptured these huge 

 vertebrae. I have met with no enunciation of this law ; and 

 until it is explained how it differs in physiological action from 

 the processes which sculpture or excavate the bones of birds, 

 it will be difficult to judge whether we are offered a law, a 

 suggestion, or only words, for no law will produce anatomical 

 etfects without corresponding physiological circumstances to 

 sculpture the bones. 



If the influence of pneumatic pressure produces a well- 



