154 ROYAL SOCIETY OF CANADA 



down between the neural spines. The dorsal fin has twenty-four rays, 

 the anal twelye, each with an equal number of supports. There are 

 about twelve rays to the ventral fins and fourteen to the pectorals. 

 In advance of the ventral fin is a conspicuous, long, rather narrow 

 bone, the basipterygium. The bones supporting the pectorals cannot 

 be made out, nor are the bones of the head satisfactorily seen. Both 

 fins of the pectoral and pelvic pairs are preserved in the specimen. 

 The caudal fin is supported by eight haemal and three neural arches. 

 Of the former the posterior seven (hypural bones) are broadened in 

 a vertical plane. A few rays appear to be attached directly to the 

 posterior end of the urostyle on its lower side above the last hypural 

 bone. The rays of the caudal are jointed throughout their length 

 and branched distally. The lateral line appears to be represented 

 above the vertebral column anteriorly by a double longitudinal series 

 of faint, short, horizontal raised lines. 



Measurements. 

 Of specimen of Amyzon hrevipinne from Horsefly river. 



MM. 



Total length (3i/^ inches) 89 



Length of head, including opercular apparatus 23 



Depth at anterior end of dorsal fin . . 23 



Depth at base of caudal fin 9 



Length of anterior ray of dorsal fin 16 



Length of base of dorsal fin 23 



Distance of posterior end of base of dorsal fin from caudal. ... 13 



Length of anterior ray of anal fin 14 



Length of base of anal fin 6.5 



Distance of posterior end of base of anal fin from caudal 9 



Length of ventral fin 12 



Distance of base of vertral fin from anterior end of anal fin. . . . 16 



Length of pectoral fin 13 



Distance of base of pectoral fin from base of ventral fin 17 



Length of vertebral column 48 



The specimens from the southern interior of British Columbia in 

 the Museum of the Geological Survey, pertaining to the genus Amyzon 

 are : — 



North fork, Similkameex river: obtained by Dr. G. M. Dawson 

 in 1888. 

 Amyzon hrevipinne, Cope, type specimen. 



