THE HAMILTON ASSOCIATION. 75 



a portion of their original color, and a beautiful Aviculapecten, with 

 wavy lines, deep umber, from the " Mountain limestone," Ireland. 



The best preserved specimens of the Lingular here are found 

 at the bluff or cliffs a little beyond the " Reservoir." They occur 

 in a large flag near the summit, " upper red band." The flag in 

 question is about 4^ inches thick, and, on splitting, it presents a 

 ripple or " wave mark " in the interior, clearly proving its deposit in 

 very shallow water. 



Casts of the detached valves of other shells (undescribed) 

 " Modiolopsis," "Posidonia" and "Avicula," are frequently obtained 

 associated with the Lingular. An Eichwaldia valve (unusually large 

 as compared with one in the " chert beds ") was also noticed. 



Casts of the single valves of "Lingula Oblonga" (color blue) are 

 very numerous. "Lingula Oblata" (pink) is rare, and "Lingula 

 Perorata" (brown shading to blue at the beak) rarer still. AH, how- 

 ever, occur on the inside of the slab, occasionally close together. 

 They represent casts of detached valves of dead shells washed up 

 and heaped together by the waves. Only in a few instances I noticed 

 both valves complete, and twice I found " Lingula Oblonga " fossil- 

 ized seemingly in its burrow. The question arises : do the shells 

 possess any portion of the original coloring matter, or is the difference 

 of color now seen due to the influence of chemical agents ? On this 

 point some Palaeontologists differ, while others hesitate to commit 

 themselves to any opinion on the subject. Now granting that recent 

 Lingular are green — may not such be the survivors of a family 

 group that at one period of its existence was represented by other 

 species quite different in color ? This seems worth investigation. 

 The Common Mussel (Mytilus Edulis) of the North Atlantic is blue ; 

 Mytilus Smaragdinus (Ceylon) is green ; Patella Vulgata (British 

 Seas) is colorless ; while the Patella of the Adriatic is deep blue. 



The colored Lingulse are not altogether confined to a single 

 horizon. In a few instances I found "Lingula Oblonga" retaining 

 a portion of blue coloring matter in an impure limestone near the 

 base of " the Clinton," and also in " the sand beds " capping the 

 series. 



A lingula (L. lamellosa) probably, from "the blue building 

 beds," Niagara limestone, also retains part, at least, of what I am 

 inclined to think was the original color of the Brachiopod. In " the 



