Plate 6 



Page 



1-8. Hederella chrhosa Hall, 1881 34 



1, The type specimen (after Hall and Simpson). 



2, Photograph of a cast of the type. 



Hamilton (Ludlowville shale), West Bloomfield, N. Y. 



3, An example with long intervals between the zooecia. 



4, Portion of a zoarium with crowded branches and imusually long 



tubes. 

 Hamilton (Ludlowville-Centerfield limestone), 3 miles west of 

 East Bethany, N. Y. 



5, A specimen referred doubtfully to the species but differing in 



the shorter intervals between the zooecia. 

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



6, Part of a zoarium with budding developed on one side only, 



reducing the distance between the zooecia but showing the 

 normal arrangement on one of the branches. 

 Hamilton (Widder shale), Arkona, Ontario. 



7, An example similar to the original type but with less distance 



between the zooecia. 

 Hamilton (Ludlowville shale), Skaneateles Lake, N. Y. 



8, Specimen with ancestrula and illustrating the less regular 



growth in the young stages. 

 Middle Devonian (Silver Creek dolomite), Charlestown, Ind. 

 9-11. Hederella Chester ensis, new species 46 



9, One of the types, illustrating the main axis giving rise to 



branches of single zooecia that curve and bud into charac- 

 teristic groups. 



10, An example incrusting a Lyropora showing the outer branches 



of the zoarium. 



11, An elongate branch incrusting a cup coral in which the curved 



aspect of the groups is not so apparent. 

 Chester group: Marion (9) and Sloans Valley (11), Ky. (Glen 

 Dean limestone), and Evansville, Ind. (10). 

 12-14. Hederella parvirugosa, new species 33 



12, Portion of zoarium exhibiting the method of division of both 



zooecia and branches. 

 Hamilton (Widder shale), Thedford, Ontario. 



13, Ancestrula and young zooecia. 



Hamilton (Ludlowville-Wanakah shale), Elma, N. Y. 



14, Portion of a mature colony, illustrating usual budding of 

 zooecia and branching. 



Hamilton (Moscow shale), Moscow, N. Y. 



15. Hederella occidentalis, new species 41 



The type specimen, a worn zoarium but distinct enough for 



description. 

 Devonian (Percha shale), Lake Valley, N. Mex. 



16. Hederella camdenensis, new species 41 



The somewhat abraded type specimen characterized by its stout 



linear branch with widely divergent zooecia. 

 Lower Devonian (Helderbergian-Birdsong shale), just south of 



Camden, Tenn. 



81 



