146 PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



collections secured from the horizon itself and from the rocks immediately 

 above and below. 



The Cambro-Devonian boundary was examined in numerous places, with the 

 following results : On Roche Miette the Devonian has been described as sepa- 

 rated from the Cambrian (in which the highest fossils now appear to be of 

 Middle Cambrian age) by a series of beds tentatively referred to the Silurian. 

 Further collections from these rocks appear to place them in the Devonian. 

 In North Kootenay Pass the Middle Cambrian is separated from the Devonian 

 by many hundreds of feet of apparently unfossiliferous strata. In the Beaver- 

 foot Range near Golden the Devonian is absent, but the section includes sev- 

 eral thousand feet of fossiliferous Upper Cambrian and Ordovician, up to and 

 including the Richmond, east of Lake Minnewanka, and in the Sawback Range 

 and upper Columbia Lake sections the Devonian rests on a series of beds 

 whose fauna is comparable in many respects with that of the Gzarkian. 



Manj' additional specimens of Triassic ( ? ) fish were secured from the fish 

 locality discovered in 1915 in the "Jurassic fault block" near Massive, west of 

 Banff, Alberta. 



Additional collections were made from the fossil locality discovered by Mr. 

 Drysdale in the Laurie Metargillite near the Laurie mi^ie, west of Glacier. 

 These are limited to crinoid stems, but appear to indicate that the Laurie 

 Metargillite is Upper Paleozoic in age. 



Additional collections were secured by Mr, Bancroft and the writer from 

 the general horizon in the Slocan series containing the doubtful fossils first 

 discovered by Messrs. Drysdale and Bancroft in 1916. These have been exam- 

 ined hj Mr. Kindle, who reports that they appear to be of Pennsylvanian age. 



Professor Williston followed with a paper on the evolution of vertebrae, 

 which was illustrated by numerous lantern slides and discussed by Doctor 

 Merriam. 



EVOLUTION OF VERTEBRJE 

 BY S. W. WILLISTOX 



{Abstract) 



The evolution of the holospondylous vertebra from the primitive embolom- 

 erous type is shown in the gradual decrease in size of the hypocentrum in 

 the caudal vertebrae of the rhachitomous amphibians and the atlas of primitive 

 reptiles to a wedge-shaped form not much larger than the dorsal intercentra 

 of primitive reptiles and by the corresponding increase in size of the embolom- 

 erous disklike pleurocentrum into the body of the centrum of the primitive 

 reptiles. It is evident that the rhachitombus amphibians have no immediate 

 ancestral relationships with the reptiles, which must have sprung directly 

 from the Embolomeri, probably in Mississippian times. 



A second interesting paper on vertebrate paleontology, dealing with the 

 paleopathology of vertebrates, was presented by Professor Williston for 

 the author. This paper, which was likewise well illustrated with lantern 

 slides, was discussed bv Messrs. Williston, Merriam. and Grabau. 



