132 



in balsam or styrax. Stained Bacteria and Micro- 

 cocci. 



Test Plate. This will be an excellent acqui- 

 sition for all those who can meet the pecuniary 

 outlay. It consists of a series of 20 diatoms ar- 

 ranged according- 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 to yoVo mcn - A specimen of Eupo- 

 discus argus begins and ends the series : 



Stiriae in y^ 

 inch. 



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



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



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



4. Navicula lyra, Ehrbg., 23. to 30.5 



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



6. Stauroneis phoenicenteron, Ehrbg., 31. to 36.5 



7. Grammatophora marina, Sm., - 36. to 39. 



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



9. Pleurosigma acuminatum (Kg.) 



Grun., - 41. to 46.5 



10. Nitzschia amphioxys, Sm., 43. to 49. 



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



12. Grammatophora oceanica, Ehrbg. 



G. subtilissima, 60. to 67. 



13. Surirella gemma, Ehrbg., - 43. to 54. 



14. Nitschia sigmoidea, Sm., 61. to 64. 



15. Pleurosigma fasciola, Sm. var., - 55. to 58. 



