118 



EARLY ADAPTATION IN STAR-FISHES. 



again with its oral surface turned toward the shell. There are many examples of 

 separated valves (one having been carried away or macerated) under which the 

 starfish lies, face always against the interior of the shell. Indeed it has proved 

 in many cases that a gentle tapping with the hammer over the surface of any of 

 the clam shells will break down a thin film of rock and expose a starfish lying 

 beneath, usually with its mouth up or towards the interior surface. Many stars 

 may attack a single clam or oyster. That is often enough seen among the oyster 

 beds and we find indications of similar habit in these fossils where a number of 

 starfish are grouped about the clams as though relaxed by death from joint 

 assault on the shell fish. 



It is not to the shell fish alone that the star devotes its lickerish taste. It is 

 omnivorous, but its attack on the clams has called into play a special adaptation 

 of its procedure. It had the problem to reach the mail-clad animal within its 

 armor and this problem it solved in the ages long gone. 



This record of a venerable practice continued down to the present does not 

 stand alone among ancient records of predatory habits. Such habits must of 

 course be presumed, even though the vestigia fail. But it is not unusual to find 

 among the mollusks of the Devonian and late Silurian faunas shells which have 

 been bored through by the tooth ribbon of the carnivorous gastropods, the circular 

 beveled holes remaining in shells of the victims with all the perfection of similar 

 evidences of attack found on the shells along our beaches today. 3 



EXPLANATIONS OF PLATES XIV, XV, XVI. 



PLATE XIV. 



Part of a slab, natural size, with a number of associated clams and starfish. At the upper right 

 are two Pterineas and one Grammysia with Palaeasters clustered in and over them in attitudes which 

 leave little doubt that they were engaged in their attacks when buried by the sediments. 



Expanded valves of Grammysia with a single Paloeaster in one of them, the oral face lying against 

 the inside of the valve surface. Natural size. 



PLATE XV. 



of 



showing one starfish, face up, lying j ust within 

 >f Grammysia. Other Grammvsias with associ 





the 



PLATE XVI. 



carrying 



example of the abundance of the starfish. Reduced. 



Mus.. nl. 12. fies. 5-7 







