Plate 13 



Page 



1. Hederella ? laxa (Whiteaves, 1891) 46 



Photograph of a gutta-percha squeeze of the holotype. 

 Devonian, 40 miles above mouth of Hay River, Canada. 



2. Hederella thedfordensis, new species (see also pi. 1, figs. 7-12) 43 



An example incrusting a Tropidoleptus and exhibiting the method of 



branching. 

 Hamilton (Moscow-Kashong shale), l}i miles southeast of East 



Bethany, N. Y. 



3. Hederella siluriana, new species 32 



View of the holotype incrusting a bryozoan, which is attached to an 



example of Protathyris didijma. 

 Silurian, Island of Gotland (probably Klintehamn). 

 [, 5. Hederella crassilinea, new species (see also pi. 4, fig. 4) 41 



4, View of the basal side of this species exhibited in the interior of a 



cephalopod shell. 



5, Part of zoarium incrusting a cup coral and showing the method 



of branching and the short zooecial buds. 

 Devonian (Cedar Valley formation), railroad fill northeast of 

 Randalia (4) and Iowa City (5), Iowa. 



6. Hederella blainvillei Clarke, 1907 42 



The type specimen, natural size, exhibiting the regular branching 



of the tubes (after Clarke) . 

 Devonian (Gaspe sandstone), Gaspe, Quebec. 



7. Hederella nrachnoidea Clarke, 1900 34 



Photograph of the type specimen incrusting a trilobite head. 

 Oriskany, Becraft Mountain, near Hudson, N. Y. 



8. Hederella ulrichi, new species 40 



Photograph of a gutta-percha squeeze of the type, X 2, and portion, 

 X 4, exhibiting the distant branching and the budding of the 

 tubes. 



Helderbergian (50 feet below top), Big Stone Gap, Va. 



9. Hederella quebecensis, new species 45 



View of a gutta-percha impression of the type, which incrusted a 



valve of Leptostrophia blainvillei. 

 Devonian (Gaspe sandstone), near Gaspe, Quebec. 



10. Hederella ramea Clarke, 1900 43 



View of portion of type specimen showing the regularly dividing 



unilinear branches and resemblance to H. blainvillei. 

 Oriskany, Becraft Mountain, near Hudson, N. Y. 



