Plate 7 



Page 

 1. Ilederella colbornensis, new species 32 



Gutta-percha impression of the type, a zoarium incrusting a cup 

 coral. 



Middle Devonian (Onondaga-Decewville limestone), Port Col- 

 borne, Ontario. 

 2-4. Hedcrella canadensis (Nicholson, 1874) 31 



2, Nicholson's figure of the Corniferous limestone specimen se- 



lected as the holotype. 



3, A topotype identified by Nicholson, showing similarity to 



//. cirrhosa but plainly much smaller. 

 4, Portion of the same, X 8. 



Middle Devonian (Onondaga-Decewville limestone), Port Col- 

 borne, Ontario. 



5, 6. Ilederella angulata (Davis, 1885) 40 



The loosely branching zoarium incrusting the noncelluliferous 



side of a Fenestrellina, and a portion, X 8. 

 Onondaga (Upper Jeffersonville limestone), Falls of the Ohio. 



7-9. Hederella tenera, new species 40 



7, 8, The zoarium, and a portion X 8, incrusting the noncelluli- 

 ferous side of a Polypora; the very narrow frequently di- 

 viding tubes are characteristic. 



9, Another example in which frequent overlapping of the branches 



gives a crowded aspect. 

 Onondaga (Upper Jeffersonville limestone). Falls of the Ohio. 

 10-1'). Ilederella concinna, new species (see also pi. 15, fig. 2) 32 



10, Young stage of a zoarium, illustrating the ancestrula and the 



less regularly branching tubes emitted from it. 

 Hamilton (Ludlowville-Wanakah shale), Erie County, N. Y. 



11, Another young specimen in which a tendency of the zooecial 



tul)es to coil at their extremity is shown. 

 Hamilton (Widder shale), Thedford, Ontario. 



12, Portion of zoarium showing change from young condition to 



mature stage where the zooecia remain nearly in contact. 



13, Portion of the same, X 8, showing change from youthful to 



mature arrangement of the tubes. 



14, Portion of a colony illustrating branching of zoarium. 



15, Mature portion of a colony attached to a Fistulipora. 

 Hamilton (Ludlowville-Centerfield shale), 3 miles west of East 



Bethany, N. Y. 



1 G. Ilederella reciif areata, new species _ _ _ 42 



Zoarium incrusting a coral and illustrating the very short zoo- 

 ecial tubes and the emission of both zooecia and branches 

 at right angles. 

 Hamilton (Ludlowville-Wanakah shale), 18-Mile Creek N Y 

 82 



