WHAT IS TRANSCENDENTAL PHYSICS? 315 



closed skeleton would imply that it was n foetus ; but it may possibly 

 have been the young of the same species, or an allied form, that had 

 been swallowed. No similar instance is known among the Dinosaurs. 



A point of resemblance of some importance between birds and 

 Dinosaurs is the clavicle. All birds have those bones, but they have 

 been considered wanting in Dinosaurs. Two specimens of Iguano- 

 don, in the British Museum, however, show that these elements of 

 the pectoral arch were present in that genus, and in a diagram be- 

 fore you one of these bones is represented. Some other Dinosauria 

 possess clavicles, but in several families of this sub-class, as I regard 

 it, they appear to be wanting. 



The nearest approach to birds now known would seem to be in 

 the very small Dinosaurs from the American Jurassic. In some of 

 these, the separate bones of the skeleton can not be distinguished 

 with certaintv from those of Jurassic birds, if the skull is wanting-, 

 and even in this part the resemblance is striking. Some of these di- 

 minutive Dinosaurs were perhaps arboreal in habit, and the difference 

 between them and the birds that lived with them may have been at 

 first mainly one of feathers, as I have shown in my memoir on the 

 Odontornithes, published during the past year. 



It is an interesting fact that all the Jurassic birds known, both 

 from Europe and America, are land-birds, while all from the Creta- 

 ceous are aquatic forms. The four oldest known birds, moreover, 

 differ more widely from each other than do any two recent birds. 

 These facts show that we may hope for most important discoveries in 

 the future, especially from the Triassic, which has as yet furnished 

 no authentic trace of birds. For the primitive forms of this class we 

 must evidently look to the Palaeozoic. 



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WHAT IS TRANSCENDENTAL PHYSICS? 



Br PAUL E. SIIIPMAN. 



THE theory of a fourth dimension of space has lately been brought 

 forward somewhat prominently, under the imposing title of 

 " Transcendental Physics," by Mr. John Charles Frederick Zollnei*, 

 Professor of Physical Astronomy in the University of Leipsic, al- 

 though the learned professor, it should be said, imputes the sugges- 

 tion of the theory primarily to Kant, and secondarily to Gauss, the 

 celebrated mathematician of Gottingen, both of whom, he says, struck 

 out the thought. In this, it is possible, the professor does himself less 

 than justice. 



Gauss had large expectations from the geometry of position, but 

 its development, as contemplated by him, does not appear to have 



