CONSl'1-CTUS OF THE FAMILIES AND GHN1-RA 



OF I'll K 



DIATOM 



SYNOPTICALLY ARRANGED HV PROF. H. L. SMITH 

 IN 'THE LENS," FOR JANUARY, 1872. 



CL A SS CRYPTC )( } AMIA. 

 Sir, CLASS ALG.E. XATUUAL ORDER DIATOMACE7E. 



[s. v. A'/Vr ]'/'<>/: f. v. Front rii'ir.] 



Plant a FRUSTULES ($ilk'i.onx bo.r), bivnlvc. t>seudo-nnicellular, 

 and with an external, more or less apparent, gelatinous en- 

 velope, and an internal investing membrane, with eiidocliromc. 

 GEMMIPAKOUS INCREASE by SELF DIVISION. KKIMJODUCTIOX 



l>y ('ONJTXJATION. 



TRIBE T. RAPHIDIE.E. 



i ;i disiind raphe and 

 nodules on one or both 



v;iives: cenl ral nodnlc 

 rarely wanting or ob- 

 si arc ; valves simple 

 01 eom])lex ; raphe 

 nerally prominent 

 i i s. v., occasionally 

 in 1'. v., especially 

 \ hen const riclcd. wit li 



a/ways with 



FEUS T u i, E s 

 mostly bacillar 



in s. v. ; some- 

 times broadly 

 oval ; 



without 



flodules at the con 



st rict ions ; 



! t< 'th, s]>incs. awns, or 

 | processes. 



