158 



On the Systematic Anyang ement of 



CARPUS. <; 



EXPLANATION OF LETTERS. 



H. Humerus. 



u. Ulna. 



R. Radius. 



u. Ulnar e = cuneiform. 



r. Radiale = scaphoid = navicidare. 



c. Centrale = central. 



i. Intennedium = lunar. 



z. Second carpale= trapezoid. 



3. Third carpale = magnum. 



4. Fourth carpale = unciform. 



II, III, IV. Corresponduig metacarpals. 



IX. — On the Systematic Arrangement of North American 

 Terrestrial Mollusks. 



By THOMAS BLAND AND W. G. BINNEY. 

 Read January 29, 1872. 



Since the publication of our work on the Land Mollusks 

 of North America,* we have had the opportunity of examin- 

 ing the animals and the lingual dentition of many additional 

 American, as well as numerous foreign species. We have 

 also carefully studied the various systems of classification 

 which have been proposed both here and abroad. The re- 

 sult of our researches is a considerable change in our views 

 regarding the classihcation of terrestrial mollusca. Such of 

 these changes as relate to the American families, we pur- 

 pose stating here, referring always to the page of our work 

 containing the description or statement to be modified. 



*Land and Fresh- water Shells of North America, Part I. 

 Feb., 1869. 



Smithsonian Institution, 



