INFUSORIA. 
51 
For what relates to the classification and synonimy of this family, I am chiefly indebted 
to an abstract of Ehrenberg’s work on Infusoria, which is appended to Mandl’s Traite pra¬ 
tique du Microscope. The generic and specific characters which I give, are in most cases 
literal translations from this work. I have also studied with much profit, Kiitzing’s Synopsis 
Diatomearum, in the Linncea for 1833. The plates accompanying Kiitzing’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. 
Poly gastric {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 polypidoms, in conse¬ 
quence of imperfect, spontaneous {longitudinal) division. 
Ehrenberg divides this family into the following group, viz : 
Desmidiacea, having the carapace simple, free, and univalve, (not usually siliceous.) 
Naviculacea, with the carapace simple, free, with two or more valves, (siliceous,) 
Echinellea, with the carapace simple, fixed, (siliceous.) 
Lacernata, with the carapace double, (siliceous, and enveloped in tubes or gelatine.) 
He separates the Closteria as a distinct family; but this genus is so closely allied to Euas- 
trum, that I cannot hesitate to follow the example of most writers upon the subject, and to 
class them with the Desmidiaceae. 
The following analytical table of the genera of Bacillaria, is translated from Ehrenberg : 
A. Carapace simple. 
A. Free. 
a. Univalve,. Desmidiacea. 
a. Prismatic. 
1. Trilateral,. Desmidium.* 
2. Glaudrilateral, . Staurastrum.* 
3. Pentagonal,. Pentasterias.* 
b. Round. 
1. Smooth. 
aa. Polypidoms moniliform,.. Tessararthra. 
bb. “ bacciform,. Spharastrum. 
2. With projections,... Xanthidium.* 
c. Flattened. 
1. In forms of bands. 
■* The question as to the correctness of Ehrenberg’s view with regard to the internal structure of his Polygastrica, appears 
still undecided. 
