BY J. DOUGLAS OGILBY, 659 



of the ventral and caudal fins, and of its own anterior semi- 

 detached portion, this fin becomes lower with increasing age. In 

 the forward position of the nuchal crest our second species 

 approaches T. rex-sahnonorum, and stands in a similar position 

 to it that T. jacksoniensis does to T. altivelis. 



In my judgment arcticus should be removed from the genus 

 Trachypterus, of which the Cepola trachyptera of Gmelin is the 

 type,* and be left as the representative of the genus Bogmarus of 

 Bloch and Schneider. 



* Jordan and Evermann (Check-List, p. 490) give trachyrhynchus as the 

 type of Trachypterus; I do not know of any such species; possibly it is a 

 jnisprint. 



