BIHANG TILL: K. SV. VET. AKAD. HANDL. BAND: 9. N:0O 5. 15 
of these reasons I think the spore-formation of this 
alga ought to be regarded as purely neutral; and be- 
cause this plant differs in such an essential respect from the 
other Mesocarpew, I have thought fit to form a new genus for 
it.!) To this I have given the name of Gonatonema (from 
yovv, yovatogs knee, and »jua filament) because of the appea- 
rance of bent knees which the filament presents when the 
formation of spores is begun. 
The diagnosis of this genus may be given thus: 
GONATONEMA nov. gen. e Mesocarpearum familia; sporis 
(agamosporis nec carposporis) sine conjugatione, tripartitione 
cellul& matris, ex media hujus parte formatis. 
As a name for the species of this genus, the history of 
which I have tried to give above, I have chosen G. ventrico- 
sum because of the appearance of the spores. 
In looking through the literature on Conjugate I have 
found another plant, described and figured so as to be with 
certainty referable to this genus. This form is Mesocarpus 
notabilis, deseribed and figured by :A. H. HASSALL?) more than 
thirty years ago. Already the first glance at one of HASSALL'S 
figures — for the sake of easy comparison copied on my plate in 
fig. 14 — is enough to convince the observer, that this plant is 
a near relative to G. ventricosum. But that they are notiden- 
tical seems equally certain. HASSALL'S species is of a consi- 
derably greater size and its spores have a different shape. 
The genus Gonatonema does, consequently, at present embrace 
two species, viz. G. ventricosum n. sp. and G. notabile (Hass.) 
nob. Of these species the following diagnoses may be given: 
have also, according to DE BARY 1. c. pag. 7, a membrane of only one 
layer. 
1) If we attached importance only to the neutral or sexual nature of the 
spore-formation, as some of the modern systematizing botanists do even 
in the lower Cryptogame, we should be obliged to form a separate 
family for it, which might not even be placed in the class of Con- 
jugate. To me the accordance with Mesocarpee as to the vegetative 
cells and the formation of the spores seems too great to allow the 
separation of Gonatonema from this family. — It may not be un- 
necessary here to call to mind, that the class of Diatomaceae, in which 
the formation of spores is in general effected through conjugation, does 
also embrace some genera where the spores are formed neutrally. Such 
is the case with the genera Melosira, Orthosira, Cyclotella and Biddul- 
plia. Compare E. PFITZER, Untersuchungen iber Bau und Entwicke- 
lung der Bacillariaceen, in J. HANSTEIN, Botanische Abhandlungen. 2 
Heft. 1871; and EL. BORSCOW. Die Siisswasser-Bacillariaceen des siid- 
westlichen Russlands. 1873. 
?) In A History of the British Freshwater Alg&e. 1845. Page 170, pl. 46. 
