98 
Lunulina proposed by Bory 1822 has been regarded 
as a synonym of that genus. 
Turpin’s description of Helierella 1823 runs 
so: ■’^Corpuscules internes cunéiformes, composes, se 
groupant dans I’epaisseur du mucus par leur côté aminci, 
et figurant comme des fasceaux divergents. Ce genre 
établit un passage aux Bacilla riées par les Navicules 
et les Syllaires”; which ought to be compared with 
the description of Heterocar pella: ”Corpuscules internes, 
indifférement simples, composés ou aggrégés.” That 
seems to show that T. regarded ”les fasceaux” as in¬ 
dividuals. (Or probably he regarded the undivided 
mucus with the plants as a thallus.) Moreover there 
exists no Micrasterias so deeply and regularly, but 
unsymmetrically divided as Lyngby e’s fig. E 3 on 
tab. 69, quoted by Turpin 1825. If really a Mi¬ 
crasterias had been sketched, it was dried and 
shrunken so as to be deformed. The figure, could 
therefore give no representive idea of a Micrasterias. 
If a genus is allowed to be founded only upon figu¬ 
res, which, I think, is not right, these figures must 
at least show the most salient diagnostic features. 
Also a description consisting of a few words of no 
value is useless. Ctr Hedwigia 1893 p. 149. 
Heterocarpella Bory 1823—25 is a genus so 
heterogeneous, that even 0. Kuntze could say ”ist 
ein genus delendum”, although Kützing 1834 and 
Brébisson 1835 have vindicated its maintenance. 
Desmidium, established by Agardh 1824 on 
Diatoma Sivartzii Ag. 1812, of which figures were 
published 1815 by A. and 1819 by Lyngbye, has 
always been regarded as a proper genus, although se¬ 
veral strange species have been included in it and 
different opinions have been prevalent as to whether 
or not some species should be elevated to generic 
rank. Such elevation of some other species has been 
universally ajDproved. 
