112 



THE NAUTILUS. 



difference may be due more or less to difference in the seasons 

 (weather) from year to year. 



Tlie facts already obtained have an important bearing on legislative 

 action already taken or contemplated for the protection and preser- 

 vation of our fresh-water mussels. Unlike the sOng and game birds 

 and the mammals, no close season will serve to protect all of the spe- 

 cies. The taking of all clams under tlie fully adult size must be pro- 

 hibited to prevent their extermination by pearl-hunters and button 

 manufacturers. 



TABLE SHOWING GRAVID PERIODS OP THE UNIONID^. 



The letter g indicates gravid individuals, n denoting that none 

 were found gravid, gn that some females examined were gravid, others 

 not gravid, either among specimens taken at the same time or in the 

 same month in different years. 



Anodonta eataracta Say. . 

 Aitodonla implicata Say. . 

 Anodonta undulata Say. , 

 Alasmidonta undulata Say. 

 Alasmidonta varicosa Lamarck 

 Lampsilis cariosus Say . . . 

 Lampsilis ochraceus Say . . 

 Lampsilis radiatus Gmelin . 

 Lampsilis venlricosus Barnes. 

 Lampsilis ligamentinus Lamarck 

 Margaritana margaritifera L. 

 Quadrula muUiplicata. . . . 

 Quadrula perplicata Conrad. 

 Quadrula trapezoides Lea . . 

 Strophitus edentulus Say. . . 

 Symphynota viridis Conrad . 

 Unio complanatus Solander . 



Vnio heterodon Lea 



Unio nasutus Say 



f 



Unio nortkamptonensis Lea. ■{ 



I 



Unio occidens Lea 



Unio rectus Lamarck 



Anodonta footiana Lea .... 

 Anodonta subcylindraceus Lea . 

 Lampsilis superiorensis Marsh . 



3 •?, 



(i, S 



g g 



g g 



g g 



g 

 g g g 



ap pr X i- 

 mately as 

 U. compla- 

 natus. 



u >^ a 

 <1 S ►^ 



gn gn n 

 g g n 



g n 



n g g 



g g g 



g g g 



gn g g 

 g g g 



< cc 



n n g 



n n g 



g 



g g 



g g g 

 g 



g g 

 g 



g 



g 



g gn n 



gn g g 



O !z; O 



g g g 

 g g g 



n n n 

 g g g 



