THE ECONOMIC MOLLUSCA OF ACADIA. 39 



is the young of the Whelli, Buccinum undatum. From this it differs iu 

 the absence of the longitudinal undulations and in the shape of the 

 lowest part of the free edge of the opening. As stated under the des- 

 cription of B. undatum, this in P. lapillus is more or less angular and 

 never lower than the lowest point (the apex being considered the upper 



Fig. I. — Turpura lapillus. Natural Size. 



■end of the shell) of the columella, or central pillar around which the 

 whorls are wound. In B. undatum on the other hand, it is always evenly 

 rounded, and always a little lower than the extremity of the columella. 

 Through all its variations, it yet presents a certain individuality of its 

 own not describable in words, which makes it easily recognizable when 

 once the student has become familiar with it. 



The Purple-shell lives upon rocky shores between high and low- 

 water marks, particularly near the latter. It rather prefers exposed 

 situations and is often found on ledges exposed to the full force of the 

 ocean swell. It is very voracious and attacks nearly all of the littoral 

 Molluscs, into the shells of which it can easily bore an opening by means 

 of its filelike tongue. One writer tells us that it can bore through the 

 shell of the common Mussel in from three to live minutes, while others, 

 with more show of probability say that it takes two days. Can not some 

 of our teachers or students who live near the shore, throw some light 

 oipon such questions at this? Through the hole, not larger than a large 

 pin head, the animal thrusts its proboscis, and sucks out the juices of 

 its prey at its leisure. The Oyster is a favorite food, and great damage 

 is done to Oyster beds by this species. In England it is considered 

 " one of the greatest if not the most destructive of the Oysters enemies." 

 It has been so bad at times on the English beds that sixpence per liundred 

 has been paid to collectors. It also attacks species of Littorina, Limpets, 

 small Naticas and its own kind. It feeds very largely upon the common 

 shore Barnacles, Balanus balanoides, thrusting its proboscis between the 

 opercular valves of that species. Its egg-cases, urn or vase shaped, 

 smooth, about one-fourth of an inch long, of a yellow or cream color tinged 

 -with pink, are found attached in groups on the under sides of stones, 

 and in crevices of the ledges, at low tide. The young remain in Ihem 

 until their shell is well-formed and they are able to shift for themselves. 



