208 BRITISH DESMIDIEiE. 



which Corda considers that both are true species. I have not seen Corda's 

 descriptions or figures, but in a subsequent work he gives the following reasons 

 under D. bifidum for belie\dng them distinct : — 



"M. Ehrenberg lui adjoint I'espece suivante, trouvee a Carlsbad. EUe en 

 diif ere totalement, du moins de celle que je considere comme la forme normale 

 du Desmidium bifidum, qui, relativement a sa structure, principalement a la 

 decoupure de ses pointes, correspond beaucoup avec le dessin incomplet d'un 

 membre separe, qu'on trouve dans I'ouvrage de M. Ehrenberg, I. c. D. bifidum 

 (bidetis dans le dessin), vu lateralement, ne presente que deux pointes prin- 

 cipales sur chaque aile, lesquelles sont simples. Quant a I'espece suivante, 

 nous avons depeint deux pointes principales, tres-visibles, et chacune d'elles 

 egalement pourvue de deux pointes." — Observ. Microscojp. sur les Animalcules 

 de Carlsbad, p. 18. 



5. D. bifidum (Ehr.). See Staurastrum bifidum. 



APTOGONUM. 



2. A. Baileyi ; filament not crenated ; joints about equal in 



length and breadth. 



Odontella 1 tridentata, Bailey, in lit. cum icone (1846). 



Worden's Pond, Rhode Island ; near Princeton, New Jersey, vdth spo- 

 rangia, Bailey. 



Filament triangular ; joints excavated at their junction like those of Apto- 

 yonum Desmidium. The joints are not bicrenate, hence the margins of the 

 filament are entire, a character which distinguishes it from that species. The 

 end view is triangular, with rounded angles. 



Professor Bailey has sent me a drawdng of the conjugated state, very in- 

 teresting from its resemblance to a condition of Desmidium Swartzii, which I 

 had doubtfully regarded as the sporangia of that species. In both plants it is 

 difficult to understand the process or to distinguish the coupled filaments, 

 since the appearance is merely that of a much-enlarged and torn filament. 



Tab. XXXV. fig. 1. from drawings by Professor Bailey; a. portion of a 

 filament ; b. transverse view ; c. sporangia highly magnified 



SPH^ROZOSMA, Corda. 



.3. S. lamelliferum (Corda). 



Sphcerozosma lamelliferum, Corda, Ohserv. Microscop. sur les Animalc. de 

 Carlsbad, p. 21. t. 4. f. 29 (1840). 



Carlsbad, Corda. 



" Chatnes courtes, les membres doubles presque uniformes ; un tiers est 

 decoupe transversalement des deux cott's ; lobes rapproches I'un de 1' autre, 

 arrondis ; cuirasse unie, transparente et blanche. Le membre de reunion 

 feuillete, blanc." — Corda, I. c. 



