OF THE DIATOME^. 



101 



second tribe, including those genera which have frondose forms, I find cha- 

 racters for my subtribes in the natui-e of the frond and the arrangement of 

 the frustules. 



''I do not propose this arrangement as free from exceptions or even serious 

 defects ; but I have adopted it in preference to those hitherto given, as bring- 

 ing more fi'equently together forms allied in structui'e and mode of growth, 

 and as being at the same time more strictly in accordance with the external 

 physiognomies of these organisms, and therefore more likely to be appre- 

 hended by the inquirer entering upon the study of this department of natui^e. 

 A wider study of Diatomaceous forms will doubtless lead to more accurate 

 and more natural generalizations." 



We subjoin the systems of classification proposed by Kutzing and by 

 Smith. The former is presented in a tabular form — 



DIATOME^. * 



Tribe I. 



Striatae. 



Tribe II. 

 Vittate. 



Tribe III. 

 Areolatae. 



Order I. 



AsTOMATICiE. 



Without a central 

 opening on the 

 secondary side. 



( * Transverse striae unbroken. 

 Family 1. Eunotieae. 



2. Meridieae. 



3. Fragilarieae. 



** Striae broken (interrupted) in the median line. 

 Family 4. Melosireae. 



Order II. 



StOMATICjE. 



With the central 

 opening. 



i 

 Order I. ) 



ASTOMATIC.E. I 



Withovit median V 

 aperture on se- 

 condary side. ) 

 Order II. ^ 

 Stomatic.e." I 

 With a large dis- [ 

 tinct one. 



5. Smirelleae. 



a. MONOSTOMATIC^. 



Family 6. Cocconeideae. 

 7. Achnantheae. 



b. DlSTOMATICE. 



f Having a median aperture on only 

 \ one of the two secondary surfaces. 



Order I. 



DiSCIFORM.E. 



Order II. 

 Appendiculat^. 

 I Appended doubt- 

 i^ ful forms. 



Family 8. Cymbelleae, 



9. Gomphonemeae, 



10. Naviculeae. 



11. Licmophoreae. 



12. Striatelleae. 



13. Tabellarie®, 



14. Coscinodisceae. 



15. Anguhferae. 



16. Tripodisceae. 



17. Biddulphieae. 



18. Angulatae. 



19. Actinisceae. 



fWith a median aperture on each 

 \ secondary surface. 



The Synoptical Table of Prof. Smith contains only those genera then 

 knoAr^Ti in Britain ; but since the date of its publication not a few others 

 have been added to the list. 



Class CRYPTOGAMIA. 



Subclass ALG^. Natubal Order DIATOMACE^-. 



Plant a Feustule ; consisting of a unilocular or imperfectly septate cell 

 invested with a bivalve silicious epidermis. Gemmiparous increase, by 



