172 



NEW YORK STATE MUSEUM 



PLATE I 



1 Part of the weathered surface of a Stromatopora from the 



Cobleskill limestone, Schoharie, N. Y., showing the open- 

 ings of the worm tubes Gitonia sipho 



2 A section of the same colony permeated with such tubes 



3 A colony of Favosites sphericus Hall from the 



New Scotland beds (Helderbergian) with similar tubes 



4 A head of the trilobite Dalmanites overgrown with a colony 



of Monticulipora in which is embedded a series of 

 Gitonia sipho. Onondaga limestone, Becraft moun- 

 tain, N. Y. 



5 Sections of spiral tubes (Streptindytes concoe- 



natus) in a colony of Stromatopora. The apparent 

 difference in direction of volution in these is due entirely 

 to the different depth and angle at which the tubes are cut. 

 From the Cobleskill limestone (Upper Siluric) Schoharie. 



X 2 



6 An enlarged restoration of the characters of these worm 



tubes. X 5 



7 Streptindytes acervulariae Calvin : tw D tubes 



in a colony of Acervularia davidsoni E. and 

 H. X 1.5. From the Middle Devonic of Roberts Ferry, 

 Iowa 



