410 ANIMAL NATURE OF DIATOMEiE. 



in the miuuter species renders uncertain the generic 

 arrangement of some among the fifteen species enu- 

 merated by Kiitzing. 



25. CoccoNEMA. — Individua ut in genere prcece- 

 denti sed stipitata, stipite ex uno apice cyvibellarum 

 crescente. 



Without concerning ourselves with the generic value 

 of the character which is wanting in six of the eleven 

 species ascribed to Cocconemce, it is most interesting to 

 consider that whilst some Cymhellm adhere parasitically 

 to submerged bodies by their ventral sui-faces, like Epi- 

 themits, the Cocconemce, again, adhere with a stipes by 

 one of their extremities. Are M^e hence to infer that the 

 adhering side may be either one of the primary surfaces 

 or one of the secondary (Cocconoidese) or finally one of 

 the extremities ? Or must we regard adhesion as a 

 primary character in judging of the organ ographical 

 correspondence of the various surfaces and different 

 types, and make other characters subordinate to it, such 

 as the one derived from the division which sometimes 

 takes place in the direction of that surface, sometimes 

 transversely to it ? Again, admitting the first case, ought 

 we not, at least, to ascribe to this character a value 

 superior to that of the presence or absence (at least when 

 they are doubtful,) of the central and terminal apertures ? 

 Or, finally, that adhesion of the only species of Cymbella 

 which is said to be parasitic {C.pediculus), is it not merely 

 ventral in appearance, as seems sometimes to be the case 

 in certain Achnanthides ? 



26. Syncyclia. — Individua cymhelliformia transversim 

 in fascias circulariter in curvas connata, in substantia 

 gelinea molli amorpha nidulantihus. 



The genus Syncyclia {S. salpa, 8. quarternaria) repre- 

 sents, among the Cymbellege, the genus Eumeridion in 

 the order Astomaticse, the Epithemia costata in the 

 family of Eunotieae. Whenever the lateral surfaces are 



