174 NEW YORK STATE MUSEUM 



PLATE a 



1 A calyx of Zaphrentis with a number of tube openings of 



Gitoniacorallophila 



2 Tubes of the same character opening outward through the 



lateral walls of Zaphrentis ; much enlarged 



3 A Zaphrentis with tube openings at the base 



4 A Cystiphyllum with short tubes opening outward through 



the thecal walls 



5, 6 A Zaphrentis from two points of view to show the course of a 

 tube of Gitonia corallophila with both ends 

 opening outward in the calyx 



All these specimens are from the Onondaga limestone 

 (Lower Devonic). 

 7 Caunopora — a schematic section showing the Syringopora- 

 or Auloporalike tubes overgrown by the Stromatopora sub- 

 stance; coral on coral 



8-1 1 Enlarged figures ofSpirorbis angulata Hall, a worm 

 tube from the Hamilton group of New York. These speci- 

 mens are silica replacements etched from limestone (Menteth 

 limestone), and show the tendency of the tube to unwind 

 in a lax spiral as soon as fixation is firmly established. 



