OF THE FAMILY BACILLARIA. 113 



To avoid the risk of adding to the ah'eady burdensome syno- 

 nymy, I have not attached any names to the species which I be- 

 lieved new, or which I could not determine satisfactorily, and 

 shall merely refer to them by the numbers given to the figures 

 representing them. I hope that these figures will enable some 

 of the learned students of this family in Europe to decide which 

 species are new ; and perhaps if this paper should meet the eyes 

 of Ehrenberg, he may oblige us by furnishing for publication 

 the authentic names of the species I have represented in the ac- 

 companying plates. 



For what relates to the classification and synonymy of this 

 family, I am chiefly indebted to an absti-act of Ehrenberg's work 

 on Infusoria, which is appended to Handle's Traite pratique du 

 Microscope. The generic and specific characters ivhich I give 

 are in most cases literal translations from this ivork. I have 

 also studied with much profit Kutzing's Synopsis Diatomearum 

 in the Linncea for 1833. The plates accompanying Kutzing's 

 memoir have decided many doubts for me. Ehrenberg's great 

 work on Infusoria I have not yet seen. 



Without further preface, I shall now present a translation of 

 Ehrenberg's characters for the 



Family BACILLARIA. 



" Polygastric (distinctly or probably*) without intestinal canal ; 

 appendices (distinctly or probably) variable, undivided, body 

 multiform ; carapace often prismatic and siliceous, with one or 

 several openings, often having the form of articulated polypi- 

 doms, in consequence of imperfect, spontaneous (longitudinal) 

 division." Ehrenberg divides this family into the following 

 groups, namely : 



Desmidiacea, having the carapace simple, free, and univalve, 

 (not usually siliceous.) 



Naviculacea, with the carapace simple, free, with two or more 

 valves, (siliceous.) 



* The question as to the correctness of Ehrenberg's views with regard to the internal 

 structure of his Polygastrica, appears still undecided. 



