1894.] MICROSCOriCAL JOURNAL. 171 



and to line many of the shores with marine material. 



Of the five deposits of fresh water diatoms which I 

 have myself discovered in Bristol, Conn., three are from 

 five to eight feet below the surface, and are each about 

 two feet thick and cover several acres ; the fourth is 

 more narrow, about two rods wide, appears to connect 

 two adjoining swam})s, and the fifth is bisected by a 

 railroad cutting. They lie at diff"erent elevations, from 

 400 to about 800 feet above sea level, and they all vary 

 considerably in the contained species as well as in rich- 

 ness, though all are rich. They all show the character- 

 istic grey ash color when dried and are light in weight. 



The deposit which underlies the neighboring city of 

 New Britian is not so rich, and contains more clay and 

 sand ; it is much more difficult to clean. It was discov- 

 ered in digging for foundations for buildings, and varies 

 in appearance, in richness and to some extent in con- 

 tained species in the diff"erent localities where it has 

 been dug up and investigated. This material requires 

 examination under the microscope to determine that it 

 contains diatoms, while the dried Bristol material shows 

 at a glance to an experienced eye that it is diatomaceous. 

 The Quinnipiac deposit also shows its diatomaceous char- 

 acter clearly when dry, but many of the shore deposits 

 require an actual test to determine their value. It is 

 probable that scarcely one in a thousand of existing de- 

 posits has ever been discovered or investigated, and col- 

 lectors are in no danger of exhausting the supply of new 

 material for many years to come. 



Chemical Analyses of the So-called Infusorial Earths. 



By ARTHUR M. EDWARDS, M. D., 



NEWARK, N. J. 



It is interesting to compare the chemical analyses of 

 the so-called "Infusorial Earths" which contain the shells 



