ANIMAL NATURE OP DIATOM KJE. 43? 



Kiitzing describes and figures the Naviculae as disfigured 

 by desiccation, I ought to state that I have observed 

 such Naviculae and thought them specifically character- 

 isticof a Schizonema, which, for this reason, 1 denominated 

 8. Cercaria. I have ascertained subsequently that the 

 Naviculae of many species undergo a similar alteration. 

 It takes place more frequently in the Micromegce or true 

 Schizonemce of that genus than in Monnemce. It ap- 

 pears that sometimes, perhaps in certain physiological 

 or abnormal conditions, the solid substance of the shield 

 is redissolved. The appendages, too, with which the 

 disfigured Naviculae seem, in such cases, to be furnished, 

 are due to the partial tube, which closes upon them 

 (vi si addossa], grows thin, and bursts. 



43. MICROMEGA. "Phycoma Jiliforme ramosum, tubo 

 communi externo cinctum, ex naviculis seriatis compo- 

 situm. Series navicularum sinyulares tubulis internis 

 minoribus propriis (secundariis] veljibris tenerrimis cur- 

 vatis bicrispis cinctfs. Spermatia immersa, ex dilatatione 

 navicularum oriunda." 



From what has previously been stated, it would seem 

 to be proved that, by the laws of nomenclature, we ought 

 to maintain the name of Schizonema for this genus : 1st. 

 Because Agardh established this genus (Sy sterna, 1824) 

 with a definition indicating an essential generic character 

 which distinguishes it from the preceding, " fila fascia- 

 formia e fills angustioribus coadunatis composita, granula 

 ettiptica includentibus, in qua iterum secedunt." 2d. Be- 

 cause, in the very description succeeding the definition, 

 he insists upon this organic condition " Composite 

 (plant <%} sunt epluribus individuis licet jiliformib us, iterum 

 includentibus eadem fere corpuscula qua in Frustulia et 

 Meridione invcnimus." Arid he adds this excellent cha- 

 racter of the mode of branching, " Rawosa apparent, et 

 ab auctoribus ita describuntur, quod tantum ex Jissione 

 filorum oritur." 3d. Of the ten species ascribed in this 

 work, for the first time, and all contemporaneously, to 



