49 



tribe,' says Mr. Tryon, in his ' Manual of Concholog},' ' is 

 the habit of agghitinating foreign bodies to the upper surface 

 of the shell, which is carried to such an extent in some 

 instances as to conceal the volutions, and give the structure 

 the appearance of a small pile of fragments of stones and 

 shells.' That this imitation of its surroundings is protective 

 in its nature there can be no doubt, but in some of the 

 species the protection is not apparent, the agglutinating 

 process being restricted within the narrowest bounds, as you 

 will see in the species A', calculifcra and A', indicns. 



" You will notice that the objects are arranged with a 

 degree of regularity as to size and occurrence, indicatmg the 

 existence of choice or artistic taste on the part of the 

 Mollusc. The specimen already referred to from Pernam- 

 buco is covered only with CeritJiium shells (a small pyramidal 

 shell about an inch in length). Of the shells attached, 

 single ones of bivalves seem to be preferred, probably 

 because they give more surface for their weight than uni- 

 valves, but you will notice in the specimens before you that 

 the Conchyliophora are mineralogists as well as shell 

 collectors, and some ' go ' for both stones and shells. 



" Now if this protection is found to be necessary by some 

 species, why not by all ? one would naturally ask ; why should 

 some go about without any or very little mask, seeing that 

 as many specimens are found in the same localities unpro- 

 tected as protected ? It is a question which I cannot 

 attempt to answer, and which, like thousands of other 

 questions continually occurring in the study of natural 

 history, we can only hope that patient study and observation 

 will some day be able to elucidate." 



In the discussion which followed, Mr. Step said that, from 

 his knowledge of the Mollusca, it would be found that 

 although it might seem that certain species were con- 

 spicuous, yet a more intimate knowledge of the habits of 

 these creatures would show that they had sufficient pro- 

 tective resemblance to preserve the species from destruction. 



OCTOBER loth, 1 90 1. 



Mr. F. NoAD Clark, Vice-President, in the Chair. 



Mr. Mc Arthur exhibited several larvas of Tripliccna comes 

 in a novel cage, made by adapting to his purpose one of 



4 



