FACTS AIJOIT WKI.I. KNOWN ANIMALS?. > ( 



its slull at tilt" sli«;lit(.'st vil>rati(»ii ami dies t'loiii a sudden 

 jar, so that a loud tliundti-<la|i will kill, instantly, a whole 

 hoat loa<l. TiuTe is nood evidence that oysters attain the 

 a.ue ot" thirty years, and no one knows how nnich l(jnii;er they 

 may live. 



Knkmiks. — Prolilieaey usually decreases as we descend the 

 scale of organic life, and yet, as Darwin has forcil)ly re- 

 nuirke^, oven tlie slow-l»reedinn- elei)iiant, if left unchecked, 

 wt)uld soon i)eoi>le the earth to the exclusion of all other 

 animals. Hence all creatures have enemies of one kind or 

 another — checks to their undue multiplication. The oyster 

 has many such. In the free swinnnini; stage the young are 

 devoured by all sorts of animals, and even after it becomes 

 fixed it is preyed upon by many, while others are truly para- 

 sitic, boring or drilling holes through its shell. 



Certain sea-worms, (Branch Annelides,) and even a boring- 

 sponge, ( Cliona mlpJiurea Verrill,) help to perforate the shell, 

 while small boring univalve mollusks belonging to its own 

 Branch do the same thing. They are known in common 

 laniiuace as '" drills" or " borers." and thev work l)v means of 

 a tongue ribbon, which is su[iplied with flinty teeth. The 

 large spiral mollusks known l»y the names of '"winkle'" and 

 *' conch," of which 1 exhibit an example, })rey upon the 

 oyster and crush its shell by sheer muscular power of the 

 large '' foot," by which they grasp it. The commonest of 

 these is Fiilgur carica. They all have an interesting life-his- 

 tory of their own, but I have time only to show you the curi- 

 ous egg-cases of the last named species, which many of you 

 have doubtless found cast upon the beach, strung together 

 as they are in a series of itarchment-like disks, diminishing 

 in size toward either end of the string. 



There is one enemy of the oyster, however, which, on 

 account of its great destructiveness and its universal occur- 

 rence along the seashore, requires more than a pa.ssing 

 notice. 1 allude to the — 



.STAK-IISII. 



Here you have one of these singular creatures, a mere 

 skeleton of its former plump .self, when filled with water. 



