R. ETHERIDGE ON ADHERENT CARBONIFEROUS PRODUCTION. 



499 



distinct from P. complectens, mihi. This is possible, as the respec- 

 tive forms differ so widely in size ; still, the question requires further 

 elucidation. I am glad to find that P. complectens is regarded by 

 Mr. Young as a form distinct from hitherto described species. 



Fig. 1. 



Fig. 2. 



a, 



Fig. 3. 



Fig. 1. Portion of stein of Poteriocrinus crassus, Miller, with the remains of a 

 large adherent body, probably a Productus. a, central depression re- 

 presenting the position of the shell ; b, spines radiating from it. Natural 

 size. Carboniferous Limestone, Auchenmade Quarry, near Dairy, Ayr- 

 shire. Cabinet of Mr. J. Smith. 



Fig. 2. Small Chonetes (?) adhering to a Productus-spine by a portion of the 

 visceral region of its shell and three of the hinge-spines, a, one of 

 the spines ; b, Productus-spine ; c, coarse radiating striae or ridges seen 

 from the interior of the shell. Six times natural size. Carboniferous 

 Limestone, Scremerston Quarry, Northumberland. Cabinet of Mr. J. 

 Bennie, Edinburgh. 



Fig. 3. The same, seen from above, a, the spines ; b, the Productus-spine. 



Fig. 4. Small Chonetes (?) or Productus (?) adherent on a Crinoid stem, with 

 spines of various lengths radiating from the circumference ; the area and 

 fissure are visible, a, median fissure ; b, hinge-spines ; c, radiating spines 

 from sui-face; d, crenulations along front margin. Four times natural 

 size. Carboniferous Limestone, Fife coast near Kinghorn, Firth of 

 Forth. Collection of Geological Survey of Scotland. 



3. Description of the Specimens. 



The more immediate object of the present paper is to direct at- 

 tention to the specimens represented by Figs. 2-4. They were 



