CORRECTIONS. 



P. XXII, line 23. — Read John H. Watters. 

 P. XLI, line 25. — Read John H. Watters. 

 P. 8, line 2. — Read Physa crandalli Baker (Physa rhomboidea 



Crandall 1901, non Meek and Hayden, 1856.) 

 P. 152, line 16. — For Esch., read Mann. 

 P. 191, line 11 from bottom. —For 7.2, read 0.72. 

 P. 291, line 16 from bottom. — For n. sp., read Mels. 

 P. 390, last line. — After Melanops insert n. sp. 

 P. 435 to 471. — For Plate I, read Plate VII and for Plate II, read 



Plate VI. 

 P. 474, line 5 from bottom. — For isotomic, read isotonic. 

 P. 476, line 20. — For determing, read determining. 



22. — For accomodate, read accommodate. 

 P. 479, line 21. — For labaratory, read laboratory. 

 P. 485, line 7 from bottom. — For cleary, read clearly. 

 P. 487, line 3. — For s, read is. 



6. — For sulphate read Sulphate. 



9. — For abou, read about and for he, read the. 

 P. 488, line 2. — Omit in. 



