340 J. W. DAVIS ON A BONE-BED IN THE LOWER COAL-MEASURES. 



and even into the Coal-measures, from which Agassiz described one 

 species under the name of 0. subulatus. This will in all probability 

 prove to belong to Mr. Davis's new genus Hoplonchus. He approved 

 of the author's proposed union of the two supposed species of 

 Gyracanthus, and agreed with him in his determination of the 

 Ctenacanths. To show the generality and wide distribution of the 

 characteristic forms of this formation, he mentioned that M. De- 

 walque had recently furnished him with examples of several of the 

 species from Central Russia. 



Mr. Etheridge remarked that the relation of the Bone-bed to the 

 Better-bed coal gave it a perfectly definite geological horizon. 



