168 THE POPULAR SCIENCE MONTHLY. 



dental ribbon, the broadly-spread pedal disk hides it, the exact 

 method of the operation is concealed. Having with the utmost care 

 witnessed a number of times the creature in the burglarious act, I 

 give the following as my view of the case : With its fleshy disk, called 

 the foot, it secures by adhesion a firm hold on the upper part of the 

 oyster's shell. The dental ribbon is next brought to a curve, and one 

 point of this curve on its convex side is brought to bear directly on 

 the desired spot. At this point the teeth are set perpendicularly, and 

 the curve, resting at this point as on a drill, is made to rotate one cir- 

 cle, or nearly so, when the rotation is reversed ; and so the movements 

 are alternated, until, after long and patient labor, a perforation is ac- 

 complished. This alternating movement, I think, must act favorably 

 on the teeth, tending to keep them sharp. To understand the precise 

 movement, let the reader crook his forefinger, and, inserting the knuckle 

 in the palm of the opposite hand, give to it, by the action of the 

 wrist, the sort of rotation described. The hole thus effected by the 

 drill is hardly so much as a line in diameter. It is very neatly coun- 

 tersunk. The hole finished, the little burglar inserts its siphon or 

 sucking-tube, and thus feeds upon the occupant of the house into 

 which it has effected a forced entrance. To a mechanic's eye there is 

 something positively beautiful in the symmetry of the bore thus ef- 

 fected it is so " true ; " he could not do it better himself, even with 

 his superior tools and intelligence. 



Oystermen also complain of ravages perpetrated by the great 

 conch. But there are two of these conchs, widely distinguished by 

 naturalists. One of them has the ujDper edge of the whirls orna- 

 mented with a projection, with bosses at uniform intervals : this is the 

 keeled conch, and is called, by Conrad, Fulgur carlca. The other one 

 has a canal or groove running round the shell, on the top of the 

 whirls : this is the grooved conch, and it has lately been named, by 

 Gill, Sycotypus canalieulatxis. The oystermen say that these conchs 

 " rasp the nib of the oysters ; " and with their large tongue-files this 

 is not hard to do. It is certainly going a great way for an analogous 

 case ; but I have examined numbers of the first-created oysters, fossil 

 oysters, in the New Jersey Cretaceous formation, and have found not 

 a few among them which had received precisely that treatment from 

 certain ancient carnivorous gasteropods. 



But the most insidious foe to the life and peace of the poor oyster 

 is the star-fish. The American species, which does the mischief, is the 

 green star-fish (Asterias arenicola). The species obnoxious to the Eu- 

 ropean oyster is the red star-fish {Asterias rubens). (See Fig. 10.) The 

 sea-star does not like water that is too brackish ; that is, it loves salt- 

 water. Whenever the Shrewsbury River is affected by the breaking 

 in of the sea, there is danger for its celebrated oysters. On several 

 occasions, at such times, the star-fishes have come up in great num- 

 bers, and utterly destroyed the bivalves. At one time so great were 



