

EARLY ADAPTATION IN STAR-FISHES. 117 



In association with these Palceasters are some of the invertebrate species 

 usual to the fauna of the Hamilton stage; occasional brachiopods, a brittle star, 

 of a few crinoids; but most in abundance are the clams of the period, large examples 

 of Grammysia and Pterinea whose valves, sometimes separated and sometimes still 

 held together by the preservation of the hinge ligament, are scattered very freely 

 over the sandy bottom. It was the natural bottom for the development of the 

 burrowing clams, a group to which Grammysia belongs, and doubtless quite 

 as well suited to the more aviculoid or oyster-like Pterinea, which rested on or 

 in the bottom with the lower valve of different form than the upper. There is 

 little doubt that the field was the proper feeding ground and habitat of these 

 clams and the evidence indicates that this being so, it was invaded by the starfish 

 which congregated in these vast numbers in order to feed on the clams. Con- 

 firmatory of this is the fact that while elsewhere in this Devonian formation the 

 pelecypods abound greatly where the deposits are sandy, the starfish has always 

 proved of desultory occurrence and we had no conception of its profusion till 

 the discovery of these deposits in Saugerties. 



The starfish is today the menace of the oyster planter in the northeastern 

 waters of our seaboard. Its voracious habits and its mode of attack on the oyster 

 beds have been made the subject of extended study. The commercial loss to the 

 industry by indulgence in these attacks has called for frequent appropriations of 

 public money in the endeavor to find a way to check their depredations. When 

 man, in setting his oyster plantation, spreads a special repast for a time-honored 

 appetite, it need cause no wonder if the invitation is enthusiastically and mul- 

 titudinously accepted. Thousands of bushels of starfish are yearly "mopped" 

 out of even small oyster plantations and only eternal vigilance of this kind can 

 ensure the survival of a profitable part of the oyster crop. The mode of attack 

 and feeding by the starfish on its armored enemy, both oyster and clam, are well 

 known now, since the experiments made by Schiemenz at the Naples Zoological 

 Station and the observations by Mead at Woods Hole. Grasping the two valves 

 with its flexible arms, some on one side and some on the other, and placing 

 its mouth at the ventral edge of the valves, the starfish attaches itself by its tube 

 feet or suckers and actually pulls apart the valves of the oyster or clam. That is, 

 it accomplishes an act that a man could not without leverage, but it does this by 

 tiring out its opponent. It pulls hard and long; its enemy pulls in the opposite 

 direction harder but shorter ; the muscular strain of holding the valves together 

 is gradually overcome by the starfish, the tired clam slowly yields, the valves open 

 and the incolant falls a victim to the eversible gorge of the starfish. 



Among the specimens of the ancient starfish are many which lie in such 

 relation to valves of Grammysia and Pterinea as to leave little doubt they were 

 buried in the sediment while in the operation of feeding. The valves of one 

 Grammysia are expanded and open flat out and a starfish lies inside one of them, 

 its ambulacral and feeding surface exposed to the inner surface of the clam shell. 

 In another the star seems to lie just outside the hinge of the expanded valve 



