Medium Powers Pleurosigma angulatum, dry, 

 stained Bacteria and Micrococci. 



High Powers Oil immersion i-io inch and 1-12 

 inch objectives, Amphipleura peliucida, Surirella gemma 

 in balsam or sty rax. Stained Bacteria and Micrococci. 



Test Plate. This will be an excellent acquisition 

 for all those who can meet the pecuniary outlay. It 

 consists of a series of twenty diatoms arranged accord- 

 ing to the coarseness of the lines. They are furnished 

 mounted both in balsam and styrax. Below is a table 

 giving the numbers, names of the various diatoms and 

 divisions on their surfaces in i-iooo inch. A specimen 

 of Eupodiscus argus begins and ends the series : 



Striae in 1-1000 

 inch. 



1. Triceratium favus, Ehrbg., 3.1 to 4. 



2. Pinnularia nobilis, Ehrbg., 11.7 " 14. 



3. Navicula lyra, Ehrbg., var., - 14.5 " 18. 



4. Navicula lyra, Ehrbg., - 23. u 30.5 



5. Pinnularia interrupta, Sm., var., - 25.5 " 29.5 



6. Stauroneis phcenecenteron, Ehrbg., 31. " 36.5 



7. Grammatiphora marina, Sm., - 36. " 39. 



8. Pleurosigma balticum, Sm., 32. " 37. 



9. Pleurosigma acuminatum (Kg.) Grun., 41. u 46.5 

 1.0. Nitzchia amphionys, Sm., - - 43. " 49. 



11. Pleurosigma angulatum, Sm., - 44. " 49. 



12. Grammatiphora oceanica, Ehrbg., G. 



subtilissima, - - 60. " 67. 



