THE NAUTILUS. 17 



of capsella Gld., and doubtless have been and will be taken for such. 

 A lot of fine examples, received from the same author, collected in 

 eastern Tennessee, and named capsella, are, to all probability, 

 nothing else but adult significans, in which the last whorl becomes 

 comparatively more voluminous and commonly more descending. 

 The spire is variable from almost flat to rather elevated, and also 

 the umbilicus shows some differences. Among lots, which to all 

 appearance, were Zon. capsellus, there were examples with a single, 

 sometimes barely perceptible, tooth. 



9. With all this, I do not feel positive, at present, that Zon. 

 andreu'si W. G. B., and significans Bid., are only the juvenile 

 forms of Zon. placentulus Shuttl. and capsellus Gld. But so much is 

 sure, that they must be desperately similar, respectively, and that 

 they need careful revision, also as to anatomy. The words of W. 

 G. Binney that the latter form " a puzzling group," become of an 

 increased meaning now. 



10. For faunistics, it may be of interest that there were a few 

 specimens of Hyal. ferrea Mse., from eastern North Carolina, 

 among the materials sent by Mrs. Andrews. In my collection 

 there is one from Randolph Co., West Virginia. Also from differ- 

 ent places in eastern Ohio it is known. 



New Philadelphia, Ohio, May, 1893. 



A KEVIEW OF VON IHERING'S CLASSIFICATION OF THE UNIONID^ 

 AND MUTELID^. 



BY CHAS. T. SIMPSON. 



Since the theory of evolution has been generally accepted, a com- 

 plete revolution has taken place in the methods of study and classi- 

 fication among biologists. All artificial systems, or those based 

 upon a single character, have either been relegated to the past or 

 are hopelessly doomed. Students who are progressive and keep 

 abreast of the times, realize that in the study of organic life it is 

 necessary to seize on to every fact which can possibly aid them in 

 classifying: embryology, anatomy, the study of its development in 

 the past as taught by palaeontology, geographical distribution and 

 habits. 



Dr. H. von Ihering, of Rio Grande do Sul, Brazil, has recently 



