Plate 1 



Page 



1-6' . Hederella filiformis (Billings, 1859) 35 



I, 2, A colony two-thirds natural size growing upon Spirifer 



mucronaius thedfordensis, and a portion enlarged (after 

 Nicholson). 



3, A typical example exhibiting the main axis with branches arising 



at almost a right angle and short, broad zooecia budding from 

 each at 45°. 



4, Portion of same, X 8, showing the zooecial budding and surface 



in more detail. 



5, Another example with slightly longer zooecial tubes, which tend 



to coil. 

 Hamilton (Widder shale), Thedford, Ontario. 



6, A Wisconsin specimen identified with this species. 



Middle Devonian (Milwaukee limestone-Lindwurm member), 



Milwaukee, Wis. 

 6', A Michigan example illustrating more frequent branching than 



usual. 

 Traverse (Ferron Point formation), Rockport quarry, Alpena 



County, Mich. 

 7-12. Hederella thedfordensis, new species (see also pi. 13, fig. 2) 43 



7, A colony with ancestrula incrusting a Tropidoleptus, showing 



the coarsely lined tubes budding rather irregularly. 



8, Ancestrular part of same colony, X 8; the suture line marking 



the budding points is quite visible. 

 Hamilton (Moscow-Kashong shale), Tile Factory, V/i miles south- 

 east of East Bethany, N. Y. 



9, An example illustrating budding of two short zooecia at inter- 



vals, from each side of the main axis and its branches. 

 Middle Devonian (Silica shale) : 2)^ miles southwest of Sylvania, 

 Lucas County, Ohio. 



10, Basal part of a zoarium in which frequent branching has pro- 



duced a compact colony. 



II, Part of the main axis of a colony incrusting a Spirifer mucron- 



aius thedfordensis in which branching has not obscured the 

 details of zooecial budding. 

 12, Portion of a colony with the main axis especially well developed. 

 Hamilton (Widder shale), Thedford, Ontario. 

 13. Hederella brownae, new species: Portion of the type incrusting a 



Spirifer og 



Middle Devonian: Taemas, south side of Murrumbidgee River, 

 New South Wales. 

 76 



