1) a PROCEEDINGS OF SOCIETIES. 
well-marked and quite distinct species), Euastrwm ampullaceum, 
E. didelta, E. ansatum, E. verrucosum, and Hyalotheca dissilicus. 
All these were perfectly identical with Irish forms. Mr. Archer, 
likewise, whilst on the subject of Desmidiacez, drew the attention 
of the meeting to a paper lately publishsd in ‘ Oversigt af Kongl. 
Vetenskaps, Akademicus Forhandlingar, Stockholm’ (1864), by 
T. J. Cleve, entitled “Bidrag till Kannedomen om Sveriges 
sdtvattensalger af familjen Desmidiee,’ in order to remark 
briefly on one or two points suggested by the observations of that 
writer. Cleve, while he justly says that some of the specifie dis- 
tinctions are founded on minute characters, states that, after the 
most careful comparison of the known forms discovered by him in 
Sweden with the figures and dried examples from other countries, 
he has been unable to detect any differences, thus, as Mr. Archer 
thought, confirming so far his own views. There was one point 
in which Mr. Archer could not coincide with Herr Cleve, and that 
was in the value as a generic character to be attached to the fact 
of the zygosphore being spimous or smooth. In his remarks 
following Arthrodismus convergens, Herr Cleve states that he has 
found this species near Upsala in a conjugated state, and that the 
spores were globular, smooth, and without spines. Upon this 
latter circumstance he was disposed to constitute a distinct genus 
for this form, separate from Anthrodismus incus, whose spores are 
beset with numerous acute subulate spines. 
Now, it is a character laid down in all books (Ralfs, De Bré- 
bisson, Pritchard, De Bary) that the short, deeply constricted 
forms have spinous zygospores; the elongate, slightly or hardly 
at all constricted, and the filamentous forms, smooth zygospores. 
But Mr. Archer had lately found some of the former, such as 
several species of Cosmarium, with smooth, non-spinous spores, 
and the filamentous Spherozosma vertebratum with spinous spores. 
It is well known that other species in the same genera have the 
spores of the opposite character in the respect alluded to; and it 
follows, therefore, that this circumstance is of specific, not generic, 
signification. Therefore Cleve would be wrong in placing Arthro- 
dismus convergens in a genus distinct from A. ‘meus and its con- 
geners, merely on account of the interesting fact of the smooth 
zygospores of the former. In regard to Peniwm Thwaitesii, Cleve 
makes the remark, as if it were singular, that he has seen the 
chlorophyll-contents formed into plates, and radiating from the 
longitudinal axis of the cells towards the periphery. But this is 
simply a generic character of the genus Penium. Cleve figures 
the example of the Clostertum which he would refer to C. lanceo- 
latum, but he docs so doubtfully. Mr. Archer thought this form 
not C. lanceolatum, but a short specimen of his own C. Pritchardi- 
anum. This latter form Mr. Archer took occasion to mention he 
had since taken again at Howth, and again conjugated and main- 
taining all its characters both of frond and zygospore. Herr Cleve 
describes in his paper several new species, which Mr. Archer 
thought well established. 
