428 ANIMAL NATURE OF DIATOMEjE. 



42. ScHizoNEMA. — Pliycoma filiforme tenue luxum, ex 

 tuho gelineo (ccelomci) ramoso naviculas abbreviatas longi- 

 tiidinaliter seriatas fovente compositum. Spermatia 

 externa simplicia tubo adnata sessilia. 



The characteristic differences between this genus and 

 the following one {Micromega) assigned by Ktitzing, 

 correspond with those proposed by Agardh (Conspect. 

 crit. Diatom. 1830), in which, after rejecting the divi- 

 sion, previously suggested by Greville, of the two genera 

 Monema and Schizonema, he is induced by observation 

 to admit it in fact, obstinately insisting on rejecting it 

 in name. It is a lamentable thing, and the primary 

 source of the confusion that all deplore in the synonyms 

 of botany and zoology, that a mistaken vanity frequently 

 induces authors to maintain their own errors with perti- 

 nacity, and blindly to reject the opinions of others. 

 Greville divides the Schizonenm of Agardh into two, 

 Monema and ScJiixonema ; Agardh maintains that the dif- 

 ference between them rests solely on a different degree 

 of organic development, which it is often difficult to dis- 

 cover ; therefore he recasts the two genera into one. 

 Somewhat later Agardh finds certain species in which 

 the character defined by Greville, as distinctive of the 

 genus Schizonema, is evident. When he discovered his 

 own error he ought to have restored to Greville both the 

 genus Monema, and the species taken from it. But it 

 was too hard a case ; so he turned round to establish a 

 new genus {Micromega), and refer to it the true Scldzo- 

 nemce of Greville ; thus taking away from that author 

 all the species that he had judiciously divided into two 

 genera. The scholars blindly follow their master. The 

 same story, changing the names, may be applied to many 

 questions of synonyms. If the two genera be really 

 distinct, their names ought to be Monema {ScJiizonetna, 

 Ag. and Klitz.) and ScJdzonema {Micromega, Ag. and 

 Kiitz.) ; nor can we adopt the opinion of Ehrenberg, 

 who, disapproving of the eUsion in the word Monema 

 {Mononenia), as if there were no legitimate examples. 



