HOW THE "BORER" DRILLS HIS HOLE. 



145 



PURPURA LAPILLUS. 



shell. The mode in which it is done has been clearly described by the 

 Rev. Samuel Lockwood, as follows : 



" The tongue is set with three rows of teeth like a file ; it is, in fact, 

 a tongue-file, or dental band, and is called by conchologists the lingual rib- 

 bon. . . . 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 di- 

 rectly on the desired spot. At this point the 

 teeth are set perpendicularly, and the curve, rest- 

 ing at this point as on a drill, is made to rotate 

 one circle, or nearly so, when the rotation is re- 

 versed ; and so the movements are alternated, until, after long and patient 



labor, a perforation is accom- 

 plished. This alternating 

 movement, I think, must act 

 favorably on the teeth, tend- 

 ing to keep them sharp. To 

 understand the precise move- 

 ment, 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 countersunk. The hole finished, the little burglar 

 inserts its siphon or sucking-tube, and thus feeds upon the 

 occupant of the house." 



These small "snails," "drills," "borers," or "snail-bores," 

 as they are variously called, belong to several species of Lu- 

 nalia, Purpura, Anachis, Astyris, Tritia, Ilyanassa, etc. ; 

 but the master and most destructive, as well as most abun- 

 dant of them all, is the Urosalpinx cinerea of Stimpson, the 

 common "drill" of the oyster-beds; and it is its eggs, laid in diminutive 

 vase-shaped capsules, which are often found attached in groups to the un- 

 der surfaces of stones. Several others of the small mollusks mentioned 

 above attach eggs in a similar way, but the drill's capsules have very short 

 stalks, or are almost sessile, and are compressed with an ovate outline, 

 while angular ridges pass down their sides. The natural home of the drill 



10 



, LUNATIA HEROS, WITH OUTLINE OF EXPANDED FOOT. 



EGG - CAPSULES 

 OF THE DRILL. 



