CONTENTS:

Notes on the variation of Ischnochiton conspicuus. By E. P. Chace 37
 
Lampsilis ventricosa cohongoronta in the Potomac River. By Wm. A. Marshall 40
 
Collecting about Guantanamo Bay, Cuba. By John B. Henderson 41
 
Amnicolidæ from Oneida Lake, N. Y. By H. A. Pilsbry 44
 
New Genera and Species of Central American Naiades. By L. S. Frierson 47
 
On the rate of growth of pond Unios. By L. S. Frierson 49
 
A new South African Nesopupa. By H. A. Pilsbry 50
 
A new Gundlachia from Guatemala. By Bryant Walker 51
 
A list of shells from the East Coast of Florida. By Bryant Walker 53
 
Collecting in Digby, Nova Scotia. By Lilian Dyer Thompson 57
 
A new type of the naiad-genus Fusconaia. By A. E. Ortmann 58
 
The Relation of snail fauna to floods. By A. Richards 64
 
William Bullock Clark 68
 
Publications received 69
 
Notes 71
C. W. JOHNSON, Business Manager,
Boston Society of Natural History,
Berkeley Street,
Boston, Mass.
Entered as Second-Class matter at the Boston Post-Office.