592 NEW YORK STATE MUSEUM 



marks of the gerontic or senile age have not been observed in 

 these colonies. 



There is no doubt that to these ontogenetic stages of the 

 hvdrosome of Goniograptus there are corresponding phyloge- 

 netic stages in the evolution of the genus, though the forms 

 leading up to Goniograptus and to the preceding multiramose 

 uichogratids are not known, the latter appearing unannounced 

 in the Cambric. 



Parallel series of growth stages of other multiramose dicho- 

 graptids have been obtained in the Tetragraptus and 

 Didymograptus bifidus beds of the Deep kill section. 

 As they serve more to verify the observations made on G o n i o - 

 graptus thureaui than to bring out new facts, their 

 description has been deemed unnecessary in this preliminary 

 publication. 



