152 ROYAL SOCIETY OF CANADA 



Cope, in his description of A. hrevipinne, and on the evidence 

 of this vertebrate, assigns the age o£ the Ainyzon beds of Colorado 

 and Nevada to the Similkameen beds. 



Dr. George Dawson in his report (p. 76 B) concludes that the 

 Similkameen beds "are probably of Oligocène (later Eocene) age"; 

 this on the evidence of (1) the plants which Sir J. William Dawson 

 regarded as referable to the Oligocène or Lower Miocene, and of ( 2 ) the 

 insects (all of which, except one, were new species) and of (3) the fish 

 Amyzon hrevipinne on which Cope based his correlation. 



The discovery of a second specimen of A. hrevipinne, this time 

 in association with a well known species of Amyzon, viz., A. commune. 

 Cope, a species distinctive of the Amyzon beds, is of importance, as 

 it points to the probable equivalency of both the Similkameen :and 

 Horsefly beds of British Columbia with the Amyzon beds as developed 

 in Colorado and JSTevada. 



Unfortunately, the age of the Amyzon beds in the typical localities 

 has not been definitely settled. Cope, in 1884, in his " Tertiary Verte- 

 brata," p. 742, expressed himself as doubtful whether they belong to 

 the Eocene or Miocene series. JLater, in 1891, William B. Clark ^ 

 placed them as low down in the geological scale as the middle of the 

 Eocene. 



In 1894 Professor Cope pointed out that with the discovery of 

 A. hrevipinne the Amyzon beds were extended beyond the then known 

 limits of South Park, Colorado and Osino, Elko county, Kevada. We 

 can now add the fourth and much more northern locality of Horsefly 

 river, B.C., which enters the west end of Quesnel lake from the south. 



The original description of A. hrevipinne is as follows: — "Form, 

 medium ; depth of body equal length of head. Fin radii ; D. 22-3 ; 

 A. 8; V. probably 11, an interruption in the order of the rays making 

 the location ol^ these rays uncertain. Seventeen vertebrae may be 

 counted anterior to the caudal region, of which 10 are anterior to the 

 anterior base of the dorsal fin. Space for two additional vertebrœ 

 exists at an interruption of the dorsal series, so that the total number 

 of precaudal vertebrae is probably nineteen, as the dorsal fin is unin- 

 terrupted. Distal caudal vertebrae and fin absent. Pectoral, ventral 

 and anal fins well separated from each other. Length anterior to 

 caudal vertebrae, 57 mm. ; length of base of dorsal fin, 23.5 mm. ; depth 

 at anterior base of dorsal fin, 25 mm. The species differs from those 

 already described in the smaller number of dorsal fin-rays, and of 

 dorsal vertebrae. The specimen on which it is based is of smaller size 



' U. S. Geol. Surv., Correlation papers, Eocene, by William Bullock Clark, 

 1891. 



