Feueuaky 12, 1904.] 



SCIENCE. 



257 



from a stem near that which gave rise to 

 the Dinosauria. 



The paper is an abstract, with some ad- 

 ditions, of the memoir ' The Reptilian Sub- 

 classes Diapsida and Synapsida and the 

 Early History of the Diaptosauria ' {Mem. 

 Amer. Mus. Nat. Hist., Vol. I., November, 

 1903). 



On the Primary Components of Verteirce 

 and Their Relations to Bibs: Henky 

 Faiepield Osbokn. Read by title. 

 The vertebrse of the Stegocephala and of 

 certain Permian Reptialia and the embry- 

 onic vertebrae of Hatteria establish beyond 

 question the fact that there are four pairs 

 of primary components, to which the names 

 neurocentra, pleurocentra, hypocentra and 

 hypocentra-pleurale may be given. Each 

 is present in pairs on opposite sides of the 

 notoehord and neural tube. The 'neuro- 

 centra ' correspond with the neural arches or 

 neuropophyses of authors. The 'pleuro- 

 centra' (Cope) form the main components 

 of the vertebree in the Reptilia, Aves and 

 Mammalia, and probably also in the Am- 

 phibia, although this fact has been ques- 

 tioned by Baur and Cope. The 'hypo- 

 centra' were first named by Gaudry, and 

 subsequently termed 'intercentra' by Cope; 

 they are primarily paired elements lying on 

 either side of the notoehord below and an- 

 terior to the pleurocentra; by Cope and 

 Gadow it has been held that they form the 

 main components of the vertebrse in certain 

 if not in all Amphibia. The 'hypocentra- 

 pleurale' (Fritsch) lie in pairs below and 

 posterior to the pleurocentra; they are 

 only found in certain Stegocephala. The 

 vertebral complex thus made up is modified 

 by the degeneration of the hypocentra- 

 pleurale and in many forms of the hypo- 

 centra; by the development of the pleuro- 

 centra uniting with the neurocentra to 

 form the centrum and neural arches. 

 Both on paleontologieal and embryolog- 



ical evidence the ribs always rise primarily 

 opposite the hypocentra; they are thus 

 placed between the pleurocentra and may 

 be described as 'intervertebral' or 'inter- 

 central. ' The capitulum of the rib is hypo- 

 central while the tuberculum is pleurocen- 

 tral in attachment. Secondarily the ca- 

 pitulum may migrate to the side of the 

 pleurocentrum, and the tuberculum to the 

 side of the neurocentrum. This rib migra- 

 tion, observed independently in many dif- 

 ferent orders of reptiles, proves that the 

 position of the head of the rib can not be 

 adduced as evidence of the homology of 

 that portion of the vertebral complex to 

 which it is attached. 



Mr. 6. I. Adams, of the U. S. Geological 

 Survey, read a paper entitled 'The Differ- 

 entiation of the Permian in the United 

 States, and the Diagnostic Value of Rep- 

 tiles as Indications of Permian Age.' No 

 abstract has been furnished. 



Other papers by Messrs. J. C. Merriam, 

 H. P. Osborn, Wni. Patten, E. S. Riggs, 

 W. J. Sinclair and S. W. Williston were 

 read by title. 



Before adjournment Professor H. F. 

 Osborn was elected president and 0. P. 

 Hay secretary for the ensuing year. 

 0. P. Hat, 

 Secretary. 



TBE MEMBERSHIP OF TEE AMERICAN 

 ASSOCIATION. 



The following persons have completed 

 membership in the association since the 

 publication of the list contained in Science 

 of December 25, 1903 : 



Adams, Charles Francis, Head of Science Dept., 

 Central High School, Detroit, Mich. 



Aitken, Robert G., Lick Observatory, Mount 

 Hamilton, Cal. 



Alt, Adolph, M.D., 3819 W. Pine Ave., St. Louis, 

 Mo. 



Andrews, Clement Walker, Librarian, The John 

 Crerar Library, Chicago, 111. 



Banta, Arthur M., Instructor, Indiana Univer- 

 sity, Bloomington, Ind. 



