i6o 



NEW YORK STATE MUSEUM 



discriminately over the coral at its A^arious levels of growth. How 

 well it struggled to maintain itself is indicated by the presence of 

 fully 30 individuals on a surface of this coral 2 inches square. The 

 single specimen of this species observed is from the Middle Devonic 

 Cedar Valley beds at Iowa City, Iowa. 



Worms and Sponges 



We find in more than a single instance among the fossil hexac- 

 tinellid sponges of the family Dictyospongidae evidences of worm 

 tubes attached to the inner wall or cloaca of the sponge and living 

 in a condition of commensalism. Such worms have been observed 

 in the species Hydnoceras tuberosum var. g 1 o s - 

 s e m a and Prismodictya telum Hall & Clarke, from 

 the sponge plantations of the Upper Devonic in western New York 

 [pi. 5, fig. 1,2]. In a considerable number of individuals of the 

 latter species from the same locality nearly all showed the presence 



of the annelid commensal and as the surface of the impression left 

 in the sands by the worm tube is in all cases crossed by the reticu- 

 lated skeleton of the sponge it is inferred that the position of the 



