UNIVERSITY OF CALIFORNIA PUBLICATIONS 

 Bulletin of the Department of Geology 



Vol. 3. No. 18, pp. 397=402, PI. 47. ANDREW C. LAWSON, Editor 



A NEW CESTRACIONT SPINE FROM THE 

 LOWER TRIASSIC OF IDAHO 



BY 



Herbert M. Evans. 

 CONTENTS. 



Occurrence and State of Preservation. 



Description 



Affinities 



PAGE 



397 

 398 

 399 



OCCURRENCE AND STATE OP PRESERVATION. 



The fossil fish spine described in the following paper was 

 obtained on a palaeontological expedition to southern Idaho, 

 during the summer of 1903, for the purpose of examining the 

 lower Triassic exposures at Aspen Ridge and Paris Canyon. The 

 spine was discovered at the latter locality by Professor John C. 

 Merriam, to whom the author is indebted for advice in the study 

 of the specimen. It was found in an exposure of the lower 

 Triassic in Paris Canyon and about one mile west of the town of 

 Paris. 



The associated invertebrate fauna was examined by Professor 

 James Perrin Smith of Leland Stanford Jr. University, who was 

 a member of the party. Professor Smith has made a special 

 investigation of both the Aspen Ridge and the Paris beds, and 

 the geologic position of the Paris horizon is best given in the 

 following note which he has kindly furnished: 



"The beds in Paris Canyon are lower Triassic but below the 

 typical Meekoceras beds of the Aspen range. They contain 

 species of the genera Meekoceras, Prionolobus , Ophiceras, Pseu- 



