PARASITISEM AMONG MISSOURI NAIADES 521 
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The author has noted a common teratologic, if not pathologic: 
condition in the shell, usually that of Quadrula quadrula Raf: 
=Q. lachrymosa (Lea) ) and also of Anondonta grandis Say; 
that is, an extremely emarginated postventral portion, due no 
doubt to the attacks of ecto-parasites along the mantle margins 
at this point. Why the attacks should be mostly made at this 
point is a question. Other results of this parasitism is a splitting 
of the gills from this post-ventral point to the dorsal side. From 
the-fact that this dividing of the gills and the “‘tucking in”’ of the 
shell take place equally on both sides we would ascribe the cause 
to that of sympathetic nervous reaction. Probably many of the 
so-called mew species or varieties that have crept into our 
catalogues on Nazades are only these pathologic or teratologic 
individuals and as a result “‘confusion has been made more 
confused.” . 
Although the lacustrine forms of Nazades are more greatly 
parasitized than those of the fluviatile due to more favorable 
ecologic conditions for the parasites, yet the formation of free 
pearls are more rare in the former since these are usually the thin- 
shelled forms that do not need to secrete such a limy or nacreous 
supply from the mantle glands. The thick-shelled forms of the 
lake or sluggish stream, however, are, as a rule, good pearl 
producers since the greater abundance of parasites under such 
conditions insure greater occasion for pearl formation. 
THE BIRD LOVER. 
BY BROTHER ALPHONSUS, C. S. C. 
The lover of birds is an enthusiast. If he were not, he would 
not be a lover of birds. Only those whose interest in any subject 
is intense and unabating can in truth be said to have enthusiasm 
in its pursuit. What, it may be asked, will lead a person to spend 
his precious time upon some matter apparently unworthy of such 
a sacrifice? There is in the thing something that awakens a 
